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18th
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Orion SkyQuest XT8 Dobsonian (480 x 203mm) Telescope
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Simplicity Quality and Performance [Update 6/24/07] Pros: Well made great optics beautiful views incredibly inexpensive.Cons: Physical size weightThe Bottom Line: A fantastic deal for a first telescope. It’s got the performance the price is right and it’s built to last. The XT8 is a classic design for learning the sky.
18th
Celestron G-5 (300 x 125mm) Telescope
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Great Scope for Less (Update 04/29/02) Pros: Light Compact Great Images Low Cost Cons: Not as rugged as the G3 (C90)The Bottom Line: Your money goes into the optics and it shows. This is a fantastic general-purpose telescope. This is really a minimalist setup for a C-5 telescope. More general information on getting a telescope is in my article on Picking a Telescope. A newer version the Omni with a larger mount has just come out and I hope to see one soon. I am dividing this review into several sections since it turned out I actually have some ground to cover on this product: Background Versions Performance Fixes for some things General Comments Background: The G5 first appeared in the 1972 as the C5 which was intended to be a smaller and cheaper version of Celestron’s extremely popular C8 series of catadioptric telescopes inroduced in 1970. Since then it has been in and out of production in several variants. The original optical tube was a miniature of the C8 even to the point of being mounted on a small twin-arm fork mount just like the larger telescope. The C8 in turn had changed the nature of amateur astronomy in 1970 when it debuted in a world where Newtonian reflectors were the only affordable option for a large telescope for amateur astronomers. The Schmidt Cassegrain Telescope (SCT) is a hybrid telescope using some elements of earlier designs to produce a multi-purpose telescope. This compromise is most visible in the SCT’s ratio of focal length to diameter or focal ratio. The focal ratios for these instruments are close to f/10 which makes them a compromise between two contradictory viewing regimes. Telescopes optimized for low magnification/ high light amplification deep sky wide field telescopes typically operate at f/6 and telescopes designed for high performance planetary or stellar viewing at high magnifications which often operate at f/14 and higher. The intermediate ratio allows the SCT to do something at both ends of the viewing spectrum- it can get decent planetary views and it can produce a fair image of a nebula or galaxy. However it will not do as well in either regime as telescopes designed specifically for either kind of viewing. The main appeal of this design was for people who had varied interests but could only afford one really nice telescope. The original orange painted C5 fell out of production for economic rather than practical reasons. Celestron discovered the decreased size made tolerance and machining for the smaller optical tube more demanding than for the larger C8 (machining tolerances are in absolute dimensions but mechanism performance depends on the ratio of sizes- thus if the parts get smaller their dimensions have to be more carefully controlled). This made the C5s actually cost more to produce than the larger C8 telescopes they were supposed to be an inexpensive alternative to. So although the first C5 was popular mobile astronomy hadn’t become common enough for compactness and low weight to be strong motivations for buyers. The SCT originally gained a strong following because it effectively deals with several persistent problems all telescope designs face: First the reflecting design eliminates the chromatic aberration problem refractors experience. Second the corrector plate design eliminates the curved field and coma problems Newtonian designs have. However the unusual figure of the corrector requires special production methods and many of the earlier examples have only mediocre optical quality. As a result by the early 1980s many felt the SCT design had reached its maximum potential and began to explore other alternatives. Among these were telescopes such as high performance refractors using exotic lens arrangements made with special fluorite glass. Although these telescopes are extremely expensive compared to their aperture they produce beautiful images and have one very different characteristic from the 8 and larger SCTs- they are easy to transport. Celestron reintroduced the C5 in 1992 as an astronomical and spotting scope after redesigning it to be easier to manufacture. This new design is the direct ancestor of the variants now in production. These C5s had white tubes with black writing. The astronomical version came on a single arm fork mount with an integral clock drive and was made to be easily detached for use as a spotting scope. Many people feel this version was the most useful ever produced while others have pointed out the single arm mount wasn’t as stiff as the earlier twin arm mount and so it isn’t as good for photography. This model was discontinued when the NexStar 5 was introduced and were around $1000 a copy. These and the spotting scopes came with a large handle mounted on the top which also served as a camera mount rail. The C5 SCT has grown up and become a very good telescope. The G5 is a C5 mounted on a lightweight equatorial mount and tripod. This is by far the most affordable astronomical version of this telescope ever offered. The setup has the option of attaching a motor to the mount to counteract earth’s rotation. The mount and telescope are available as a set for $750 list or $699 for the telescope and mount with no drive. At the moment Woodland Hills Camera has an ad in Sky and Telescope offering the G5 with motor for $699 (their site www.telescopes.net does not mention this promotion). I have periodically seen it on Adorama (www.adoramacamera.com) for as low as $649. If you want to get the optical tube and nothing else look at the listing on www.astroptx.com. About the time the G5 came out the handle/ camera mount was deleted from the spotting scope so the various versions had finally converged to one mechanical design with differences only in paint used and accessories included with them when sold. I ended up getting the version currently sold as a spotting scope and then mounted it to the same mount as is used in the G5. The reason for this was I already owned the mount (I had been using it with a C90- if you want that story see my review on the G3 or the C90) and Adorama Camera (www.adoramacamera.com) had fantastic deal going on the C5 spotting scope. The only difference between the C5 spotting scope and the G5 is the C5 spotting scope is painted white with black lettering on the side while the G5 is black with orange lettering on the side. The only real difference is in the peripheral components sold with them. As a side note the optical tube is also the same as the NexStar 5 which has a steel colored metallic painted tube and no lettering. Otherwise the three telescopes are the same optical device. Interestingly the mounting bracket for the C5 spotting scope is the same as the one on a G5 so it readily mounts to a CG-3 tripod with 2 1/4-20 bolts (it even has a clearance hole for the mount head bolt machined in it). The NexStar 5 cannot be removed from its mount without voiding your warranty. During the 1990s competition from other designs such as recently introduced Russian medium to large size Maksutov telescopes which while more expensive than SCTs have higher image quality at high magnifications have threatened the SCT’s dominance in amateur astronomy. Recently produced SCT telescopes I have looked through all had far better image quality than any I have seen in the past. Others have commented on this as well and I would guess the appearance of both the apochromatic refractor and the high performance Maksutov telescopes can most likely be credited with the recent improvements to the SCT. Also note- do not hesitate to adjust collimation- the difference in image quality between an almost collimated scope and a collimated scope is night and day with these things (see the fixes section below for some tips on this). Performance First and foremost this telescope has met and exceeded all of my expectations for it. On one end its resolution is so good I have started going through Sky and Telescope’s double star list for summer and discovered it can be quite a bit of fun to split doubles. At the other end of the viewing spectrum I have been quite surprised to discover its contrast is good enough to see M57 (the ring nebula in Lyra) in the city (between a Home Depot and a 20 screen cineplex) without a light pollution filter. The C90 is really a neat little telescope in a lot of ways but the C5’s performance is in another league entirely. The moon has become an entirely new field to me with this telescope. When I was 7 years old my parents bought me a Japanese made 60mm refractor from Sears. The first view of the moon I had with it amazed me as I saw the craters in relief for the first time. Much later a 5.5 Newtonian and the C90 showed very sharp views of the moon but I had forgotten what it had been like to see it for the first time. This telescope has given me that experience again. On the moon the detail has been nothing less than astounding. At 166X I have discovered fine crevasses in the lunar surface and seen the shape of low lying ridges as well as mountains and other features. In short it has felt like seeing the moon for the first time again. During the winter I have been observing Jupiter Saturn the Orion Nebula The Pleiades some double stars and the usual winter sky crowd. I have come to really look forward to using the C5- it is still light enough to just pop outside with but it is also giving beautiful images of the planets and other objects. One tip- boost magnification on nebulas to bring out the structure- yes it goes against the popular wisdom but when you get to around a 12mm eyepiece the structure suddenly becomes distinct from a light polluted sky. Mars showed quite a bit of detail during its 2001 close approach. The polar cap was visible as were some of the shadow features. One should remember Mars is a very difficult low contrast observing target; the imagews you see in print are highly processed with boosted contrast. The actual planet is a pale peach color. All in all I have been happiest with the images of Saturn which is positively 3-D with beautiful striping and detail in the rings. Jupiter is quite pretty as well. The stripes and other details refeal their inner twists and knots when the seeing is good. The great red spot (which is as many have pointed out less great and quite beige these days) is visible in this telescope. Jupiter’s moons are not only obviously little balls of different sizes but their colors are visible too. The sulfur covered moon IO is a bright amber color for example. The design of the C5 uses a moving mirror focuser arrangement where the entire primary mirror shifts forward and back to focus. A knob on the back of the telescope pushes on an arm mounted to a sleeve carrying the primary mirror along the central baffle tube. This makes the tube extremely compact and eliminates the need for moving the primary mirror for collimation. The C5 can reach focus between 20 ft. and infinity while using a large variety of optical devices ranging from eyepieces to binocular viewers to cameras. Unlike the Meade SCTs which have simple machined metal knobs the C5 has a nice large focuser knob with a rubber grip which is easy to find in the dark The range from minimum to maximum focus is about 40 turns of the knob so extremely fine focus is possible. The only real difficulty with this type of focusing mechanism is moving from forward to reverse while focusing has some lag and the image moves slightly. The commonly recommended method for focusing an SCT is to move the mirror well below focus and advance it to focus and stop. I have found getting sharp focus isn’t a very big problem with this telescope since it doesn’t have a noticeable shift when reversing the focus direction. However there are companies such as Apogee (www.apogeeinc.com) which offer separate refractor type focusers for SCT telescopes. This makes the telescope longer and heavier as a single unit but if you really don’t like the way SCTs focus you do have an option. The mount with the G5 version of this telescope is the same one as used with the smaller G3 telescope. The tripod I have been using has wood legs with the G5 mount head (the G5 sold today has aluminum legs). The mount uses a simple spring-loaded screw thread for the declination axis (north to south) which allows about 15 degrees of travel in that axis. I have found I really don’t like this method that much (I’d rather have a real worm gear) and I have put a marking on the screw shaft with a magic marker so I can judge when I’m about to run out of travel. To use the mount you need to point the hub roughly at the pole star and then release the two axes to move the telescope to a viewing object. In practice this is a lot easier to do than it sounds at first. The telescope mount needs to have its axis tilted to your observing site’s lattitude. To use the telescope simply walk outside with the tripod and set it down with the hub pointed roughly north (eyeball it). This will be good enough for visual observations. If you want to do photography you will need to follow a procedure for precision polar alignment. Celestron tells how to do this on their website at www.celestron.com. You will also need to have a motor to do this. However the amount of drift error while visually observing an object is usually pretty low on the time span of a few minutes of viewing before going to another object. The mount is very easy to use. The equatorial axis has a worm gear with steel gears. The main mount adjusts via simple tightening knobs. To point the telescope at an object I have developed a technique which seems to have overcome the usual problems with sighting on an object. For this to work the finder scope must be aligned with the main telescope as outlined in the instructions. What I have been doing is looking at the object I want to see in the telescope with both eyes. Then I look through the finderscope with one eye and keep the other eye open looking at the object. It is surprisingly easy to tell where the cross hairs are pointed while doing this. What I do then is simply push the telescope until the crosshairs appear to move to the object. The object will pop into the finderscope’s field of view just as the crosshairs approach it. Then all I have to do is tighten the axle releases on the mount and then use the worm gears to fine-tune the pointing at the object. This technique actually works well enough to center objects at 125X. So it is generally very easy to find objects with this telescope setup and the mount is actually pretty easy to use this way. If you are looking for a dim object select an easily visible star nearby and sight in on it. The mount has an interesting feature where the counterweight arm rotates in synch with the declination head. As a result it should be possible to attach a camera to the arm in place of the counterweight to make a pretty neat photo-guide scope setup that is very light (even without the tube mount rail the earlier C5s had). However the arm on mine was loose when new and tightening it up proved to be somewhat difficult since it has a threaded end with three set screws from the sides holding it in place (yeah- it’s really strange. I have no idea why it is made this way). The possibility of mounting a camera is still there although I haven’t seen a mounting shoe for doing this (there must be a part out there that does this though- maybe for something made to mount on a lab ring stand). The tray included for holding eyepieces and other parts is split up between .96 accessory holes a couple for 1.25 oculars (one of which is blocked by the tripod attachment tab). In practice the tray as supplied is worthless since items set on it can easily be knocked off and lenses with caps on both ends can’t fit into the holes. All in all this mount is easy to use. The quality is OK although I am prompted to wonder how much it would cost to do the few small extras like a full declination gear a better weight arm attachment and maybe a simple polar alignment scope. On the other hand other mounts are available and if you want another mount the telescope can be adapted to it. In the meantime this has turned out to be a light weight and easy to use system. As before with the C90 I can take it outdoors for 20 minutes of looking around and come back in. No time is needed to set it up only one assembly has to be moved and there is no need to go through a setup routine for a guidance computer before it will do anything. That kind of simplicity has a lot of appeal to me. Something also to keep in mind when comparing this telescope to expensive computer driven models is the use of a Go-To telescope disqualifies the user from getting Messier or other object certificates from the astronomy league . The astronomy league sponsors an activity to certify people who have found all 110 Messier objects as well as other object catalogs on their own through their local observing groups. Use of a telescope with the ability to find these objects automatically defeats the purpose of this activity which is to encourage people to master the layout of the skies. In the case of using a telescope with children or others the moment of discovery when one finds something for themselves is a large part of the fun as well as being a great builder of both confidence and bonding between people. Issues with Design The only real issue with the design I have found is one faced by all catadioptric telescopes with glass corrector lenses in the front- dew. The large glass corrector lens cools down and makes an ideal spot for dew to form. A dew shield is essential for preventing the formation of dew on the telescope optics which can bring your evening viewing to an abrupt end unless you have a blow dryer along. There are heater tapes sold for this but they are usually not that good an idea because the tape causes convection currents in front of the telescope which degrade the image. The dew shield also keeps stray light from outside the area you are looking at from entering the telescope and decreasing contrast in the image Fixes Telescope: The only serious problem I’ve had with the telescope itself has been dew fogging the corrector lens in front. So I made a dew shield for it. I found some 2mm thick 8.5X11 sheets of black foam sold at Wal-Mart in the crafts area for $0.66/ sheet. I bought two of these. The outer diameter of the C5 optical tube is 5.75 at the front and a little math shows the circumference is 18 so I cut two sheets and put them together with a 1 overlap using hot glue (use the low temp setting). The resulting cover just slips on the front like a sock and a little bit of adjustment makes it circular. So far it has kept the dew away and the naturally flat black interior is perfect for reducing glare. Best of all it is really really cheap (Usual going price for a C5 dew shield is $30). This shield is also a bit longer than the usual dew shields so it should be more effective in any case. Collimating SCT systems is simply a fact of life- as the instruction manual says it makes a huge difference but is very easy to do under the night sky. Collimation is done by looking at the image of a star in the sky and adjusting the secondary mirror to correct it. This is far easier to do if you have a motor drive so the star doesn’t keep drifting out of the field of view. I upgraded the forward cell with a finger-adjustable version of the collimation screws called Bob’s Knobs (www.bobsknobs.com). Just specify what the telescope is and they are $16 delivered- and well worth it. Make sure you follow the instructions to the letter when installing and it is easy. With these a screwdriver isn’t needed to collimate the scope; instead you just look in the eyepiece and then turn the appropriate screw by hand. Tip- always point your diagonal and eyepiece in the same direction when collimating. For example have them pointing opposite the mount shoe. The reason for this is after you have done this a couple times you will know what turning any one screw will do. As a result you will be able to do this very quickly. If you don’t sharply jar the scope it can hold collimation for a very long time. Tip for the folks at Celestron: Talk to Bob about making his knobs the standard equipment on your SCTs and they will be better for it. Observation on losses of collimation: Everyday use and jostling causes the collimation to degrade. Repeated temperature changes (such as taking it outside in summer or winter) will cause a little bit of drift also. This is enough to visibly degrade the image after a few months of use. However recollimation if done frequently only consists of very minor adjustments. I recommend doing a quick check now and then. Note- over-tightening the collimating screws does not help hold collimation- it causes the secondary mirror to be warped (this is called Pinch and degrades the image. Remember the images are never so clear as they are with a fresh alignment so it will be a minute well spent. Mount: The biggest problem I had with the mount was the rather pathetic tray it came with. I made a tray enlargement out of a gray plastic utility box which I cut to fit with a Dremel tool and then drilled holes in the tray and mounted the utilit box using its original screw-holes. The box is just big enough to fit all of my eyepieces into with their caps and the depth of the tray doesn’t let them topple out while carrying the assembled telescope. The only other modification I made to the mount was to add a marking to the declination axis axle so I could tell if it was at one end or the other of its range. General Comments: The C5 does everything it is supposed to and does it extremely well. To someone who has never owned a telescope before I know the prospect of dropping $700 on one seems daunting. In the case of the C5 I have been pushing its performance in every regime I can think of and after I have been using it for a while I feel it is an incredible bargain. The smaller 90mm telescopes are small enough to take backpacking but 5 or 127mm of aperture combined with very well made optics makes for a huge improvement in performance. Compared with larger telescopes than this one they perform poorly in the light pollution of the city and are far more difficult to move. This telescope is a very practical answer for someone who wants good performance and portability rolled into one. There are other telescopes such as 4 apochromatic refractors which can fill this same roll but they cost four times as much. In the case of this telescope I would now have to say it would be a far better first scope for a beginner than a small computer-guiided scope since the money goes into a very good optical tube assembly and practical mount instead of a limited 80mm or 90mm scope with a difficult to use electronic drive system. Unlike a Dobsonian this scope can support interest ranging from planets to nebulae to photography to daytime observing. Recommended:Yes
18th
Orion SkyQuest¿ XT6 Classic Dobsonian (354 x 150mm) Telescope
(No Ratings Yet) Loading ...Posted by Josh under Telescopes
The Minimum Minimalist Telescope Pros: Simple rugged construction. Good performance on Planets and the Moon.Cons: Saving $100 means a major cut in performance compared to XT8.The Bottom Line: Works well on planets and the moon: solid value for a low-end telescope. If you can afford to go from $270 to $370 consider the Orion XT8. The Orion XT6 Dobsonian Telescope is a smaller member of the XT series Dobsonian telescopes from Orion. Except for minor modifications these telescopes have remained unchanged since they were introduced and have been standing up to use. The XT6 is a third smaller in diameter 7 lbs and $100 cheaper than the Orion XT8. However given the additional capability of the XT8 I would recommend that scope over this one unless the money really is an impossible hurdle. These are currently sold for $270 which makes them a solid value for the money considering what they can do. More general information on getting a telescope is in my article on Picking a Telescope. Background Dobsonian telescopes are the most famous creation of John Dobson a one-time Buddhist monk who realized the night sky would be far more accessible if a large telescope could be made cheap enough and simple enough to operate for people to view it. The telescopes bearing his name Dobsonians have been a revolution in amateur astronomy. The concept behind the Dobsonian telescope was to find a way to put all of the money and effort into improving the telescope’s performance with as little spent on the mounting and other hardware as possible. The configuration Dobson arrived at was to make as large a Newtonian reflecting telescope as possible and mount it on a simple turn table with a fork to support it. The telescope was designed to be simply pushed in the direction an observer wanted to go. There was no gearing no precision bearings no tripod no drives no equatorial heads; just a telescope on the minimum of equipment needed to point it. This configuration makes them look sort of like large artillery pieces aimed at the sky. This led to a movement in San Francisco CA in the early 1970s where amateurs ground their own telescope mirrors and built telescopes out of cardboard carpet tubes and plywood. What they let people do was take in high quality views of large celestial objects with very little investment. In the mean time Dobson and the church parted ways. The legacy of this has been a group of avid sidewalk astronomers in San Francisco and these amazingly user-friendly telescopes. When telescope companies started building Dobsonians several refinements appeared. Teflon pads in the bearings allowed telescopes to glide more smoothly and higher quality mirrors improved performance. However they made an unusual split- on one end extremely high quality truss tube telescopes with fine woodworking appeared. Other manufacturers produced rather shoddy scopes made from cardboard with lousy optics. The middle ground for the average user who wants a practical and simple telescope was vacant until Orion introduced the XT series telescopes in the 1990s which have proved to be a near-ideal commercial version of the Dobsonian concept. Description and Usage The Orion version of a Dobsonian uses high quality steel-tubed Newtonian and mounts it on a laminated plywood stand. The mount has Teflon pads and a very smooth turntable. To make the telescope more stable it has a set of tensioning springs which pull the telescope against the Teflon bearing pads. Teflon has an unusual property where its sliding friction and starting friction are about the same. As a result something sliding on a Teflon pad will not jump when it starts. The springs overcome the balance problem many Dobsonians have which results in the telescope trying to dip or rise depending on what is in the eyepiece holder. The Orion XT6 is a compact telescope with a relatively small barrel which moves very easily- when going to objects you take the tube and just push it the way you want it to go and it will move there. After an object is in the field of view gently nudging the tube is all that is needed to keep it centered. The later versions of this telescope have a drawer-pull sized knob near the front end to give the user something to hold on to (easier that trying to grab the barrel over and over). My main complaint on this feature is it is black so it doesn’t show up at night- it should be white so it would be visible in starlight. The tube will stop when you stop pushing and it is easy to make fine corrections. This is literally a telescope where you can walk outside set it down and just point it at something immediately. Unlike a Go-to telescope there is no setup or slewing to wait for. And especially unlike an equatorial mount there is no 45 minute tedious polar alignment procedure (and yes I am only that fast on nights with superior mojo to help). The first time I saw one of these was at the local telescope shop in New Orleans. This was a brand new product and had just shown up at the same time as the XT8. I had brought back a Meade Plossl lens and was thinking about trading it in for something else. This one was already set up so it was pretty easy to be able to slew it around and try it out then compare with a larger XT8. Like the other XTs The construction is first-rate. The end fittings are well made die castings to hold the tube in-round. The steel tube was covered with uniform black enamel. The focuser was surprisingly well made and very robust. It moves smoothly and is very solid. It has a locking screw to adjust its tension so it won’t slide out of focus. The assembly is fairly heavy at over 34 lbs and it is a bit unwieldy with the optical tube attached do the base. But if you are driving to an observing site most people should be able to handle the tube and mount separately without a problem. As with all Newtonian telescopes collimation is part of life. This appears to be the hardest part of using one of these since it isn’t possible to look in the focuser and adjust the screws at the back of the telescope at the same time. So plan on lots of iterations and make sure you do a good job and lock it down so you don’t have to do this as often. If you are using a laser collimator it makes it a lot easier but more importantly all you need to do is put the telescope where you can see where the return beam is hitting. Since it currently comes with a laser collimator this is the way to go and kudos to Orion for offering such a useful accessory with an entry level telescope. Across the way from the shop is a mall where one of the buildings a quarter of a mile away was brick. I slewed the telescope to it to see if the mirror and put in a Celestron Ultima eyepiece I had tried out in the XT8. There was no distortion- the XT6 gave a perfect image. The lines in the bricks did not converge at the edges- a very flat field of view. Note the image is very obviously dimmer in this telescope than the XT8 since they both have the same focal length but the XT8 has a mirror 33% larger in diameter which gives it 77% more image brightness. In photography terms the XT6 is an f/8 while the XT8 is an f/5.9 and so the XT8 is pulling in a lot more light in the same size image. It wasn’t until later that I got to see what an XT6 is like under the stars. It is fun to use and the optical prescription is well adapted to giving sharp images of planets. Here the smaller size than an XT8 does not hurt as much since planets are fairly bright so this is actually a bit more comfortable to look at. This is a telescope which works best for things you can see some trace of by naked eye since it is a bit limited on its light grasp. Because the focal length is the same as the larger XT8 the image fields are the same magnification and the differences are due to mirror size. Since the XT8 still isn’t at the point of extreme focal rations of f/4.5 and lower there isn’t a big difference such as coma or other optical defects. The main difference I can point to is the XT6 shows planets with a lot of contrast and sharp focus. Luckily the night I got to give an XT6 a workout had a thin crescent moon in the sky and here as on planets the telescope delivered a color free image with sharp detail. In this case the image has an advantage over the XT8 which produces a painfully bright image of the moon. In this case the XT6 image jumps out with craters and fine features clearly visible. On brighter nebulas this telescope has a fairly good defense against light pollution. The limited brightness means you don’t have to push up magnification as far as the XT8 to get your eye to see through light pollution (this only works visually- this is not a photographic mount for dim objects). What you do is slowly move up in magnification and what looks like a slight blur on top of a light polluted sky will suddenly jump out when the eye is able to differentiate the image from the background (I know this sounds odd but it works well). So objects such as Orion or the Lagoon nebulas can be seen in the city this way. The Plieades star cluster just barely fits into a field of view unless you use a special wide angle eyepiece. Where this telescope ends up being somewhat wanting to my mind is it isn’t quite able to keep following the user to deeper sky and more difficult images the way the XT8 can. Because of this the $100 difference between the XT6 and the XT8 is essentially buying the ability to go deeper into the same size images the XT6 can produce. Of course if that $100 is the difference between having a telescope or none then of course the XT6 is the choice. What this telescope does for $270 was simply unavailable 10 years ago and it certainly is a massive improvement over the typical 60mm refractor labeled with the absurd claim of
18th
Orion SkyQuest¿ XT6 Classic Dobsonian (354 x 150mm) Telescope
(No Ratings Yet) Loading ...Posted by Josh under Telescopes
The Minimum Minimalist Telescope Pros: Simple rugged construction. Good performance on Planets and the Moon.Cons: Saving $100 means a major cut in performance compared to XT8.The Bottom Line: Works well on planets and the moon: solid value for a low-end telescope. If you can afford to go from $270 to $370 consider the Orion XT8. The Orion XT6 Dobsonian Telescope is a smaller member of the XT series Dobsonian telescopes from Orion. Except for minor modifications these telescopes have remained unchanged since they were introduced and have been standing up to use. The XT6 is a third smaller in diameter 7 lbs and $100 cheaper than the Orion XT8. However given the additional capability of the XT8 I would recommend that scope over this one unless the money really is an impossible hurdle. These are currently sold for $270 which makes them a solid value for the money considering what they can do. More general information on getting a telescope is in my article on Picking a Telescope. Background Dobsonian telescopes are the most famous creation of John Dobson a one-time Buddhist monk who realized the night sky would be far more accessible if a large telescope could be made cheap enough and simple enough to operate for people to view it. The telescopes bearing his name Dobsonians have been a revolution in amateur astronomy. The concept behind the Dobsonian telescope was to find a way to put all of the money and effort into improving the telescope’s performance with as little spent on the mounting and other hardware as possible. The configuration Dobson arrived at was to make as large a Newtonian reflecting telescope as possible and mount it on a simple turn table with a fork to support it. The telescope was designed to be simply pushed in the direction an observer wanted to go. There was no gearing no precision bearings no tripod no drives no equatorial heads; just a telescope on the minimum of equipment needed to point it. This configuration makes them look sort of like large artillery pieces aimed at the sky. This led to a movement in San Francisco CA in the early 1970s where amateurs ground their own telescope mirrors and built telescopes out of cardboard carpet tubes and plywood. What they let people do was take in high quality views of large celestial objects with very little investment. In the mean time Dobson and the church parted ways. The legacy of this has been a group of avid sidewalk astronomers in San Francisco and these amazingly user-friendly telescopes. When telescope companies started building Dobsonians several refinements appeared. Teflon pads in the bearings allowed telescopes to glide more smoothly and higher quality mirrors improved performance. However they made an unusual split- on one end extremely high quality truss tube telescopes with fine woodworking appeared. Other manufacturers produced rather shoddy scopes made from cardboard with lousy optics. The middle ground for the average user who wants a practical and simple telescope was vacant until Orion introduced the XT series telescopes in the 1990s which have proved to be a near-ideal commercial version of the Dobsonian concept. Description and Usage The Orion version of a Dobsonian uses high quality steel-tubed Newtonian and mounts it on a laminated plywood stand. The mount has Teflon pads and a very smooth turntable. To make the telescope more stable it has a set of tensioning springs which pull the telescope against the Teflon bearing pads. Teflon has an unusual property where its sliding friction and starting friction are about the same. As a result something sliding on a Teflon pad will not jump when it starts. The springs overcome the balance problem many Dobsonians have which results in the telescope trying to dip or rise depending on what is in the eyepiece holder. The Orion XT6 is a compact telescope with a relatively small barrel which moves very easily- when going to objects you take the tube and just push it the way you want it to go and it will move there. After an object is in the field of view gently nudging the tube is all that is needed to keep it centered. The later versions of this telescope have a drawer-pull sized knob near the front end to give the user something to hold on to (easier that trying to grab the barrel over and over). My main complaint on this feature is it is black so it doesn’t show up at night- it should be white so it would be visible in starlight. The tube will stop when you stop pushing and it is easy to make fine corrections. This is literally a telescope where you can walk outside set it down and just point it at something immediately. Unlike a Go-to telescope there is no setup or slewing to wait for. And especially unlike an equatorial mount there is no 45 minute tedious polar alignment procedure (and yes I am only that fast on nights with superior mojo to help). The first time I saw one of these was at the local telescope shop in New Orleans. This was a brand new product and had just shown up at the same time as the XT8. I had brought back a Meade Plossl lens and was thinking about trading it in for something else. This one was already set up so it was pretty easy to be able to slew it around and try it out then compare with a larger XT8. Like the other XTs The construction is first-rate. The end fittings are well made die castings to hold the tube in-round. The steel tube was covered with uniform black enamel. The focuser was surprisingly well made and very robust. It moves smoothly and is very solid. It has a locking screw to adjust its tension so it won’t slide out of focus. The assembly is fairly heavy at over 34 lbs and it is a bit unwieldy with the optical tube attached do the base. But if you are driving to an observing site most people should be able to handle the tube and mount separately without a problem. As with all Newtonian telescopes collimation is part of life. This appears to be the hardest part of using one of these since it isn’t possible to look in the focuser and adjust the screws at the back of the telescope at the same time. So plan on lots of iterations and make sure you do a good job and lock it down so you don’t have to do this as often. If you are using a laser collimator it makes it a lot easier but more importantly all you need to do is put the telescope where you can see where the return beam is hitting. Since it currently comes with a laser collimator this is the way to go and kudos to Orion for offering such a useful accessory with an entry level telescope. Across the way from the shop is a mall where one of the buildings a quarter of a mile away was brick. I slewed the telescope to it to see if the mirror and put in a Celestron Ultima eyepiece I had tried out in the XT8. There was no distortion- the XT6 gave a perfect image. The lines in the bricks did not converge at the edges- a very flat field of view. Note the image is very obviously dimmer in this telescope than the XT8 since they both have the same focal length but the XT8 has a mirror 33% larger in diameter which gives it 77% more image brightness. In photography terms the XT6 is an f/8 while the XT8 is an f/5.9 and so the XT8 is pulling in a lot more light in the same size image. It wasn’t until later that I got to see what an XT6 is like under the stars. It is fun to use and the optical prescription is well adapted to giving sharp images of planets. Here the smaller size than an XT8 does not hurt as much since planets are fairly bright so this is actually a bit more comfortable to look at. This is a telescope which works best for things you can see some trace of by naked eye since it is a bit limited on its light grasp. Because the focal length is the same as the larger XT8 the image fields are the same magnification and the differences are due to mirror size. Since the XT8 still isn’t at the point of extreme focal rations of f/4.5 and lower there isn’t a big difference such as coma or other optical defects. The main difference I can point to is the XT6 shows planets with a lot of contrast and sharp focus. Luckily the night I got to give an XT6 a workout had a thin crescent moon in the sky and here as on planets the telescope delivered a color free image with sharp detail. In this case the image has an advantage over the XT8 which produces a painfully bright image of the moon. In this case the XT6 image jumps out with craters and fine features clearly visible. On brighter nebulas this telescope has a fairly good defense against light pollution. The limited brightness means you don’t have to push up magnification as far as the XT8 to get your eye to see through light pollution (this only works visually- this is not a photographic mount for dim objects). What you do is slowly move up in magnification and what looks like a slight blur on top of a light polluted sky will suddenly jump out when the eye is able to differentiate the image from the background (I know this sounds odd but it works well). So objects such as Orion or the Lagoon nebulas can be seen in the city this way. The Plieades star cluster just barely fits into a field of view unless you use a special wide angle eyepiece. Where this telescope ends up being somewhat wanting to my mind is it isn’t quite able to keep following the user to deeper sky and more difficult images the way the XT8 can. Because of this the $100 difference between the XT6 and the XT8 is essentially buying the ability to go deeper into the same size images the XT6 can produce. Of course if that $100 is the difference between having a telescope or none then of course the XT6 is the choice. What this telescope does for $270 was simply unavailable 10 years ago and it certainly is a massive improvement over the typical 60mm refractor labeled with the absurd claim of
18th
Orion SkyQuest¿ XT10 (600 x 254mm) Telescope
(No Ratings Yet) Loading ...Posted by Jay under Telescopes
Simple Works Well Can Do a Lot and It’s Inexpensive? Pros: Well built bright images very capable package.Cons: Large difficult to pack in a small car.The Bottom Line: The XT10 is an outstanding value. It may not be as good a choice for a beginner as the XT8 though. The Orion XT10 Dobsonian Telescope is part of a series of telescopes showing what standing the test of time is all about. Except for minor modifications these telescopes have remained unchanged since they were introduced and have been standing up to use. Some have been all the telescope their users needed while others have been a gateway to other scopes but they are at a useful size and work well so generally they stay in use. These are currently sold for $550 which makes them an amazing value for the money considering what they can do. More general information on getting a telescope is in my article on Picking a Telescope. Background Dobsonian telescopes are the most famous creation of John Dobson a one-time Bhuddist monk who realized the night sky would be far more accessible if a large telescope could be made cheap enough and simple enough to operate for people to view it. The telescopes bearing his name Dobsonians have been a revolution in amateur astronomy. The concept behind the Dobsonian telescope was to find a way to put all of the money and effort into improving the telescope’s performance with as little spent on the mounting and other hardware as possible. The configuration Dobson arrived at was to make as large a Newtonian reflecting telescope as possible and mount it on a simple turn table with a fork to support it. The telescope was designed to be simply pushed in the direction an observer wanted to go. There was no gearing no precision bearings no tripod no drives no equatorial heads; just a telescope on the minimum of equipment needed to point it. This configuration makes them look sort of like large artillery pieces aimed at the sky. In the beginning none of the hardware for something like this was available and amateurs had to build their own. This led to a movement in San Francisco CA in the early 1970s where amateurs ground their own telescope mirrors and built telescopes out of cardboard carpet tubes and plywood. What they let people do was take in high quality views of large celestial objects with very little investment. Something to keep in mind here is there is a scarcity factor in telescopes as they get larger and the price increases exponentially. So while you can know the local observatory has a 30 diameter telescope the average person simply never had a chance to look through something anywhere near that size so getting a large number of these telescopes built was revolutionary in that it put a lot of very dim celestial objects on common observing lists. In the meantime Dobson and the church parted ways. The legacy of this has been a group of avid sidewalk astronomers in San Francisco and these amazingly user-friendly telescopes. Eventually the Dobson design was adopted by telescope manufacturers and given how difficult it is for the average person to grind a good mirror this had the potential to make large scopes even more available. When telescope companies started building Dobsonians several refinements appeared. Teflon pads in the bearings allowed telescopes to glide more smoothly and higher quality mirrors improved performance. However they made an unusual split- on one end extremely high quality truss tube telescopes with fine woodworking appeared combined with very expensive optics. Other manufacturers produced rather shoddy scopes made from cardboard with lousy optics. There appeared to be no true middle ground for the average user who wants a practical and simple telescope. That was the case until Orion introduced the XT series around 2001. Description and Usage When the Orion XT Dobsonians were introduced they were a clear departure from other designs with a high quality steel-tubed Newtonian in place of a cardboard tube and it was mounted on a laminated plywood stand. The mount has teflon pads and a very smooth turntable. To make the telescope more stable it has a set of tensioning springs which pull the telescope against the teflon bearing pads. Teflon has an unusual property where its sliding friction and starting friction are about the same. As a result something sliding on a teflon pad will not jump when it starts moving. The springs overcome the balance problem Dobsonians had until this deign was introduced which results in the telescope trying to dip or rise depending on what is in the eyepiece holder. Previously Dobsonian owners had to become adept at difficult techniques like carefully shifting the heavy primary mirror to balance the telescope when collimated. The Orion XT10 moves very easily- when going to objects you take the knob on the tube and just push it the way you want it to go and it will move there. After an object is in the field of view gently nudging the tube is all that is needed to keep it centered. The earliest versions of this telescope didn’t have the drawer-pull sized knob near the front end to give the user something to hold on to. My main complaint on this feature is it is black so it doesn’t show up at night- it should be white so it would be visible in starlight. The tube will stop when you stop pushing and it is easy to make fine corrections. This is literally a telescope where you can walk outside set it down and just point it at something immediately. Unlike a Go-to telescope there is no setup or slewing to wait for. And especially unlike an equatorial there is no 45 minute tedious polar alignment procedure. The first time I saw one of these was at the Deep South Regional Stargaze an annual star party held at Percy Quinn State Park in Mississippi. Here the telescope was under nice dark skies so it is a perfect environment to try it out. The telescope is very obviously larger than its sibling the smaller XT8 8 diameter telescope. The F/5 focal ratio still yields a telescope low enough to the ground for most people and kids to be able to look through it fairly easily. The eyepiece is on the left side of the barrel so guiding tends to be with the left hand. The telescope is large enough for collimating it to be a two step process between the main mirror at the back and the secondary at the front. Since the telescope currently comes with a laser collimator this is a lot easier to do than it would be using other methods which require going back and forth to look in the focuser for each adjustment. The Orion laser collimator is basically a centered laser pointer with a target drawn on it. The way it is used is to simply move the mirrors until the beam from the collimator hits the center of the main mirror and then bounces back to the center of the collimator. What makes this easier is the reflection target in the collimator is now visible from the outside so you can see where the spot is hitting while moving the primary mirror. Since this telescope is at f/4.7 it isn’t very forgiving in performance for misalignment so checking this after a significant move (like a car trip) is time well spent. The 1200mm focal length of this telescope is close to the 1250mm focal length of a scope I have the f/9.8Celestron C5. What is interesting here is the XT10 has twice the diameter and four times the area but the magnification and field of view with any given eyepiece is almost exactly the same. So the XT10 was able like the C5 to just barely fit the entire Plieades in a field of view. But the image is very different. The C5 has a flat field and the Plieades definitely have a diamonds on velvet effect. But having said that the image in the XT10 is very obviously brighter and more stars are visible. On another favorite object of mine the Double Cluster it is a similar story. The C5 does well for a telescope its size but the XT10 makes it easy. If I was to nitpick it is pretty clear the image in the XT10 is a bit curved compared to the C5 but that really comes from one of the reasons the Schmidt Cassegrain design of the C5 exists- for photography where a flat field means better focus. Since Dobsonians are visual instruments this isn’t so important. On brighter objects like planets the difference isn’t quite so clear. The XT 10 does show more detail but when going between the two the feeling I got was it was clarifying features the C5 hinted at rather than showing things not visible in the other scope. Something to keep in mind here is the XT10 brings in a lot of light and planets like Jupiter are so bright they can be painful to look at. The moon really should be viewed with a dimming filter or else it will feel like staring at a flood light. The XT10 is fair sized though I think it will be able to fit in most SUVs or minivans the fit in smaller cars is going to cause problems. The reason is the barrel of the optical tube is getting fairly large and of course you need to load it so nothing is setting on top of it where it can get dented. Since it is a foot in diameter and 4 feet long it’s going to take up some volume and the base is the size of a dining room chair. This comes to a critical point in comparing this telescope with the coffee can sized C5; it’s a lot bigger and more difficult to move. And that is important because it will need to get to the countryside to really show what it can do. In comparison the C5 is less affected by light pollution so I have found it to be quite useful in the city. The trick the XT10 has the C5 doesn’t is being able to accept 2 format eyepieces. The larger barrel allows a bigger light column into the lens which means a bigger apparent field of view can be seen. Where this is useful is a large format eyepiece like the Celestron 32mm E-Lux will give a very comfortable open view with dim objects like galaxies far more visible than with just about any other type of telescope. This is the mode where a Donsonian really is the most fun to use. Unfortunately though the telescope has the nice 2 focuser Orion only includes two 1.25 format Plossls (the 25mm lens does OK for sweeping but nowhere near as well as one of the 2 format eyepieces can). The 9X50mm finder works reasonably well for getting into the ballpark of objects though I personally like being able to sight along the barrel. The finder’s 90 degree diagonal is convenient for getting the image near where you will be looking into the telescope but getting it close enough to the object is the real trick. A lot of people use a device called a Telrad or the smaller Rigel systems Quickfinder [they both are sort of like miniature heads up displays from fighter planes] as finders. Another option is a red dot finder. Any one of these is under a $50 addition so if you find pointing to be a problem there are things you can do about it. One concern many people have is not knowing where things are in the sky to look at. However something to keep in mind is the telescope acts to take an image and make it brighter and larger. So if you can see something is there then it’s going to get better when you use the telescope. The upshot is the good stuff is visible to your eye. The Moon Jupiter Saturn the Pleiades The Orion Nebula The Lagoon Nebula Double Cluster and Albiero are all naked eye objects. If you just point the scope at anything that looks like a bright star (not the sun) or a fuzzy patch in the sky or look at the moon as it goes through its phases you’ll get to see something nice. And something to try with a Dobsonian like this telescope is to just putting in a 2 low power eyepiece and sweeping along the sky. This will cause you to run over a lot of neat objects. For example if it is summer and you follow along the ecliptic (the plane the planets travel in- identify a couple planets in the sky and you are in business) and cross the milky way in the vicinity of Saggitarius (it looks like a teapot) you will run into the Lagoon Nebula as well as several star clusters. A little sweeping in this area has several more bright nebulas like the Trifid. Another area to try this in winter is the region around Cassiopia which looks like a stretched W across the north pole from the big dipper. A more subtle comparison for this telescope is with its sibling the excellent Orion XT8. The most obvious difference here is $370 for the XT8 versus $550 for the XT10. They come with the same accessories and the designs are otherwise very similar. The XT10 is more telescope with 60% more light gathering capability and about 25% more resolution and is at the same focal length as the XT8. This means the real difference is a lower focal ratio and greater ability to go after dim objects or to make nebulas and star clusters significantly brighter at the same magnification as the XT8. The frustration here is you will need to get under the stars away from the city to really appreciate the difference. Yes the higher light gathering capability of the XT10 will make the image hold up better if using a light pollution filter but the XT8 will show less need for the filter in the city. The question here is if the XT10 should be a beginner’s first telescope. Going over $400 is a big deal for a lot of people experimenting with astronomy as a hobby. In truth the f/6 prescription of the XT8 does an awful lot. In the past I have had no trouble in a recommending the XT8 over the smaller XT6- the difference between them in cost is small while the performance difference is enormous. Between the XT8 and the XT10 the cost difference is a bigger step but the performance difference isn’t so obvious. In absolute terms the XT10 is more capable but I expect most beginners will find it takes quite a while to feel like they are outgrowing the XT8. Conclusion The Orion XT10 is a beautifully executed version of John Dobson’s vision for making deep sky astronomy accessible to everyone. This telescope is well built and from looking at ones which are several years old I would expect it to last indefinitely. Eventually the base may start to deteriorate but that will take a lot of hard use first. Remember to dry it off if it gets covered with Dew and this will be less of an issue. While some complained about the steel tube early on this means they aren’t starting to fall apart after a few years of getting dew on them from time to time. The XT10 is a very good value at $550 especially since Orion has started bundling more accessories with it including a laser collimator. If cost is a driver the XT8 is certainly a capable alternative. Otherwise the XT10 is more telescope for visual observing than $550 have ever bought in the past.Recommended:Yes
18th
Celestron NexStar 80GT (189 x 80mm) Telescope
(No Ratings Yet) Loading ...Posted by Matt under Telescopes
I ScopeBot- The mini goto telescope has arrived Pros: Inexpensive light weight portable compact easy to use surprisingly good images easy upgradesCons: Odd battery pack needs powerThe Bottom Line: It does all of the basics and does them well. The NexStar 80GT is a compact refractor with a computer driven mount. All of the structural elements are metal yielding a very solid and stable platform despite the small size and modest cost. More general information on getting a telescope is in my article on Picking a Telescope. Description The NexStar 80 GT is one of six telescopes Celestron has built using the same miniature version of a NexStar robotic computer controlled telescope mount. This version has the same 80mm diameter f/5 or 400mm focal length refractor which as been sold for a bit over 5 years by Orion Celestron and various other companies in many colors on various mounts. These telescopes have come to be recognized as what a beginner’s first scope ought to be: (1) Inexpensive enough to give it a try (2) Capable of showing the most impressive objects (3) Easy to use (4) Rugged (5) Flexible Unlike previous incarnations this telescope is now equipped with a motorized drive base controlled by a small hand computer with 4000 of the most interesting astronomical objects in the sky built in for it to automatically guide to on command. It sounds cool but my first question was Does it really work? I bought one of these as a Christmas present for my sister and her husband. Whenever they are visiting my home (which if you have inferred from my other reviews is a sort of telescope farm my wife would concur) we always do some observing. Although they haven’t been serious astronomers they are interested in observing since the views are always very pretty compared to photos. But they have always found the knowledge barrier intimidating. I thought I would give this telescope a shot as a possible answer. It came in a surprisingly small box. Inside we found a light weight tripod and the telescope attached to its mount separately. The telescope comes with every tool needed to put it together including a real screwdriver which is only actually needed for 2 screws on the finder scope. We had it put together in about half an hour. The tripod was finished in a gunmetal colored finish and the telescope tube is painted in a steel colored metallic finish. The mount had a small cover for its lower base which had come free in shipment but just popped back in to place. The mount threads on to the tripod with a single knob and the tray/hand controller holder threads on to the tripod with a single captive screw. I took this screw out and installed it from the top instead after looking at how it was going together. This is a different tripod tray than the one shown in the instructions (much easier to install). When assembled it was extremely light at 11 lbs. I was reminded of years ago when I got the C90 and it changed astronomy for me since it was light enough to walk out and use it on a moment’s notice so I used it more than heavier scopes I have owned. The telescope is fairly rugged with all metallic construction except for more minor fittings. The dew/glare shield slides off the front to make cleaning the glass easier if you are so unfortunate as to have to do this. (DO NOT TOUCH THE GLASS IF YOU CAN AVOID IT. SMACK FINGERS AWAY IF YOU HAVE TO). I was happy to find these scopes have improved with time. There is a baffle part way down the optical tube and all of the lenses are coated- they have even gotten rid of a small screw which protruded into the optical path in earlier versions of this telescope and degraded the image. Usage The telescope has a couple of odd features we noticed. First the batteries don’t go in the mount. The mount arm and base have an aluminum rigid structure with plastic covers sealing up the electronic parts. The batteries are stored in a little pouch with a small strap on it with a cord coming out. The plug on the cord is the same one any other nexstar power supply has so you would use an AC converter or car plug cord by plugging it in to the same spot. There is no ON/OFF switch- the scope is ON when plugged in (you can also plug it in to the wall or to a car with a nexstar 12V adapter). The hand controller has no start-up as most computer users are used to- it is immediately ready to start operation. It will ask what model telescope it is amongst the types using this mount when it is first powered up but will never ask this again (it is easy to change in the utilities menu in case you put in the wrong one). The controller stores its last location and time of operation but has no way of orienting itself without help. To get the telescope ready to observe the computer needs to know how it is positioned on the earth and then the precise orientation of its mount as it is setting on the ground. To do this it will first ask you where it is. You can answer this either in terms of your local latitude and longitude (if you have a good map or a GPS unit) or by looking yourself up in a nearby city from the list in the manual. It will then want to know what the local time is and what time zone you are in. It is actually able to resolve this for any spot on earth so if you are in Fiji it will work just fine. The scope asked to be pointed North and have the tube leveled. We did this by dead reckoning. We were first setting this up in New Orleans and I happened to know we were within a mile of 90W 30N so I punched it in. It asked for the time and we punched that in. It then made a guess at where the star Aldebaran was and started moving. It goes at 4 degrees per second which is actually pretty fast. When it stopped it was in the right general area of the sky but was nowhere near being close enough to see Aldebaran in the eyepiece. The telescope asked to line up the object using the finder which is a sort of miniature heads-up-display like a fighter plane uses except this just projects a red dot in the window as if you had a laser sight. However when you haven’t aligned the site with the tube it won’t work and you can’t do this until you get the telescope centered on a distant object to use for alignment. So we moved the tube until it looked like it was pointing at the star by eye and got Aldebaran into the field of view. The wide angle field this telescope has with a low power eyepiece makes this much easier since you will see the object if you get within 2 moon diameters of it. We told the controller it was centered in the finder and it asked to center it in the telescope. We switched to the high power eyepiece and centered the star. At this point we turned on the pointer and centered it so we could use it the next time. I have heard you sometimes have to adjust the dovetail where the finder grips the arm it is on but it was actually pretty close in this case so all we had to use were the finger knobs on the finder. The little red dot can be brightened and dimmed by turning the on/off knob. When we were done aligning the finder we pressed the Align button and the telescope saved the position of this star. It then took off for the star Sirius. Now if a star is below a tree or other object you can press UNDO to reject it and it will pick something else. It will never try to slew to something below the horizon. After centering the second star which was much faster with the pointer working the controller said NEXSTAR READY. This mount does have a manual version of this alignment process where you do all the steering and a quick align which assumes you pointed it perfectly north and got it perfectly level to start. When alignment is done it reminds you to turn the pointer off to save the battery. The pointing accuracy was good enough for every object to be in the field of view so we didn’t need the finder to go to a pre-programmed object. The different number buttons on the controller all have other functions. For example one button says Planets another says M (for messier) and one says Stars and so on. By pressing planets the controller will offer up a list of the moon and planets above the horizon at this time. Interestingly it won’t do the sun- but you need a special filter to observe the sun anyway. [NEVER try image projection with this telescope- at this diameter you will burn parts and maybe people. NEVER try to use an eyepiece solar filter even if it says it came from Zeiss- they can and do fail suddenly without warning from tiny invisible wear scratches in the glass from handling. This causes instantaneous and permanent blindness to anyone looking when this happens. These should be smashed with a hammer to make sure a child isn’t blinded by one). On Saturn we were surprised to find it showed the Cassini division in the rings the white cummerbund stripe around the middle and one of the orange-brown stripes on the edge of the white stripe. Two of Saturn’s moons also were visible. The focus was nice and crisp and there was none of the false color people complain about when we popped in a barlow and took it up to 133 power the limiting practical power for a telescope this size. It still looked good and even showed some gradient detail in the stripes. Something else we noticed was the mount is very steady even with the legs fully extended and the feet on hard concrete. Vibration damped out almost instantly when you let go of the focuser. On Jupiter the scope does show some false color. There is a blue-violet halo around the planet. The lens cap for the front of the telescope has a sub-cap in the center for stopping it down. We tried this and Jupiter dimmed down became a bit clearer and the blue-violet halo vanished. This is because stopping the scope down only uses the center of the lenses where they are less curved. Although this theoretically reduces the resolution it can improve the image for bright objects because full spectrum light doesn’t come to a perfect focus at the eyepiece in this type of telescope. Saturn had looked clearer because it is mostly amber colored while Jupiter has parts which range from red to amber to blue and has large areas in white. If you press the TOUR button the telescope will make a selection of neat things to see in the sky from its other databases. For some reason it doesn’t include the planets (perhaps because these are transient in their location). The best objects visible from where we were in the city were the Orion Nebula Double Cluster and the Plieades. The Orion Nebula showed up as a fuzzy area in the center of the field of view at low power. From there I remembered how other telescope behave when the power is increased so I did so and the cloud detail popped into view at 40X. At 80X the trapezium and cloud detail around it was extremely sharp. Interestingly the chromatic aberation was gone on dimmer objects like this since they are mostly visible in only one color anyway. This object was a real crowd pleaser. We found if you press the INFO button while the telescope is tracking an object it will tell you what it is what its coordinates are how far away it is and what its magnitude is. On the Plieades the scope showed the entire nearby star cluster at once. The stars had a diamonds-on-velvet appearance and even had a large swath of sky around them visible. This was easily one of the more interesting views I have seen of this object. The stars came through as little pinpoints. The only complaint is some of the blue tint visible in a Schmidt Cassegrain or Maksutov was missing. Double Cluster was another pleasant surprise as the entirity of the two star clusters together were visible at the same time. In the case of ancient star clusters like these which have been orbiting our galaxy for billions of years the stars are quite old and tend to be white yellow or red. The colors appeared to be very nice. I just wish we had had a darker sky so more of the dimmer stars could be visible. We tried it out on some double stars such as Polaris (yep- the North Star is a double star! Didn’t know that? That’s OK- if you look up double stars the telescope lists it for you). The scope showed Polaris and its dim companion. It was even possible to split Rigel which has a very close and very dim companion star. Epsilon Lyra the benchmark double-double star wasn’t in the sky. I will have to see if I can visit them during the summer to give that one a try. Details to Remember First watch what is happening with the power cord and be ready to shift the battery bag. We just had it hanging on a tripod bolt at the top of one of the legs and saw the cord could get wound around the mount if you didn’t pay attention. Second once it is slewing to something wait for it to get there before pressing more buttons. A couple times this seemed to confuse it. It has a little spinning icon it shows in the upper right corner of the hand computer while this is going on so just wait before doing more. Third remember the RATE button. Many times it will select a speed for the little cursor keys to move the telescope. Often it will be a rate slower than what you want. The rates are slowest at 1 and highest at 9. Too slow? Press rate and it will show the current speed and the next number you press will be the new speed. Once you get used to this it is pretty easy to do. The scope knows where the eyepiece and back of the telescope go and so it won’t let you run them into the tripod legs by pointing it straight up. So there are some objects right above you it won’t track to. You can point at them manually if the scope happens to be between tripod legs but keep track of where the focuser and such are so you don’t crash into the tripod. The telescope automatically guides at new rates at new locations in the sky if you drive it there with the electronic controls. It won’t lose its alignment as long as you don’t force it to move by hand (not using the motors). So if you are out and see something cool bud don’t know what it is just drive the scope to it and take a look. The scope will automatically track with the earth’s movement. Unfortunately it doesn’t appear to have the ability to ask it What in your database is near this location? You’ll need to look it up on a map. Something immpressive about the telescope is how quiet it is when tracking. When it is slewing around there is electric motor noice but if there is any sound at all- conversation traffic etc. it is so quiet that you may wonder if it is working. I personally find it far more agreeable than the strange crunching sound the Meade equivalents make. Because of this I suggest leaving the lights on the display on. It uses a little more power but you can remember it is running and not leave it on if you don’t mean to. Also the controls were designed to be easy to use. If you ever press a button you didn’t mean to press UNDO until you see something familiar. The listings for functions are meant to be logical so just look around. The instructions appear to be fairly good so that helps too. Conclusions All in all everyone was very happy with the telescope and how it performed out of the box. The two eyepieces it has are OK quality but there are other options which aren’t all that expensive. I would suggest getting a small set of Plossl eyepieces in about 6mm 10mm 15mm 20mm 25mm and 30mm sizes with a short barlow to do everything this scope can do. If you want to get just a couple to start 6mm 15mm and 25mm are probably a good spread. A car plug adapter or AC adapter may be a good idea so you don’t have to use the little battery pack. The scope is surprisingly easy to move around so it can be taken along for a picnic or other outing. It has the ability to be put in hibernation mode and you can add objects of your own (astronomical and on the ground). So if you are leaving it set up somewhere for an extended period and have a cover to keep it clean you could actually power it down and remember where it is and where objects you looked at before are. This perhaps could be done on an extended camping trip. I have already found myself wishing these were around when I was a kid. I found it to be a lot simpler and quicker to get this telescope to do something than I expected. It is surprisingly capable and well made for something you can find for $250 from www.adorama.com. For someone who has been a purist about You’ve got to learn the sky! this telescope has been reason to re-think that position. Updates The biggest change here is on possible upgrades from this telescope. First the Baader Contrast Filter from Celestron. I have a review for this component. Essentially it suppreses the false color in the image and improves contrast in images. Because it knocks down blue light it is also acts as a light pollution filter. Second the excellent Celestron 80ED 80mm apochromatic refractor will instantly take the place of the 80mm tube the 80GT comes with because they have the same barrel diameter. you would remove the tube clamp the 80ED comes with and put it in just like the 80mm short tube. With accessories the 80ED will balance with the tube forward in the clamp and with its black gloss paint job should look as good as it perfroms. This telescope is available for $408 from www.handsonoptics.com and I have a review for it as well. This telescope has a 2 focuser so you could get wider field images and also has no false color. so better resolution is possible. This is in my view the most cost effective upgrade for a major change in performance. Hopefully Celestron will offer this outstanding configuration in the near future. Finally if you want to do something completely different the small NexStar GT scopes like this can be readily converted to take another telescope tube with what is called a Baader Bracket from www.alpineastro.com. This takes the telescope and its mounting ring off of the mount and replaces it with a dovetail slot and bar. This lets any scope up to about 10 pounds take the place of the small 80GT tube. So you could for example put a C5 spotting scope on or anyhing else you felt like as long as it was relatively light and compact.Recommended:Yes
18th
Celestron NexStar 8GPS 11052 Telescope
(No Ratings Yet) Loading ...Posted by Josh under Telescopes
The All-Purpose Space Viewing Machine Pros: Anything it does it does wellCons: Too bulky for quick-looksThe Bottom Line: It’s still the answer to the question: If you were to get one scope what scope should it be? It is beautiful it works well and the views are incredible. The NexStar 8 GPS is the descendant of a line of telescopes dating to 1970 when the first Celestron C8 appeared. It is the telescope which changed amateur astronomy. The 21st Century has seen this model become new again and the results are amazing. I had always wanted one of these and now that I have one it has become an interesting education. This review ended up being more difficult to write than I expected- this is a very capable piece of equipment in several unrelated ways and this makes reviewing it complicated. More general information on getting a telescope is in my article on Picking a Telescope. Background I have already written about the genesis of these scopes in my review of the Celestar 8 so there is more information there. These telescopes were derived from a design Estonian optician Bernard Schmidt developed to make large photographic telescopes with flat fields of view in the era before hyperbolic mirrors could be reliably made. Hyperbolics are not cheap so giant telescopes from the Keck to the Hubble space telescope are Ritchey-Cretiens with complex hyperbolic optics but they are rare among amateurs. In the 1960s the people behind Celestron realized the Schmidt design previously used for observatory survey cameras was very practical for making an extremely compact telescope compared to its focal length. The spherical main mirror makes producing a high quality telescope easier since figuring and optical testing can be very accurate for this shape. The trick is to correct the light path with a specially shaped corrector plate which overcomes both the spherical aberration of the main mirror and eliminates the strong coma effect Newtonian telescopes have where stars to look like little comets at the edge of the field of view. This hybrid telescope was intended to be an all-purpose instrument where it would be a mid way between a long focal length (f/15 or higher) and short focal length (f/5 or below). This results in an f/10 telescope which has a flat field of view across its available image. This optical design is the most physically compact available. A Schmidt Cassegrain Telescope or SCT typically has proportions similar to a mid-sized coffee can at any diameter. A Newtonian reflector or a refractor will be as long as or longer than their focal lengths. As a result a moderate focal length Newtonian a 6 diameter f/8 is around 4 feet long. A 6 f/7 refractor is typically even longer and an achromatic refractor optimized for planetary viewing will be longer still since it will operate between f/15 and f/20. These instruments are enormous and require giant sized tripods and mounts to wield them. In comparison an 8 diameter SCT is under 2 feet long and far lighter than either the Newtonian reflector or the Refractor in a smaller diameter. Even more interestingly this scope is able to take in many deep space objects but still has a focal length long enough to do something on planets. This scope matured as the C8 in 1970 and changed everything. People could get a single large aperture telescope compact enough for one person to move and cheap enough to get one. It changed amateur astronomy because it did some of everything and did a fair job at it. The NexStar 8 GPS This variant follows several computer guided versions of this telescope. Most important of these was the Ultima 2000 from 10 years ago the direct predecessor of this instrument. With the Ultima 2000 Celestron introduced a computer guided telescope capable of finding 10 000 objects with a fairly simple setup and able to operate as an equatorial mount or do something new- track objects in alt-azimuth mounting where the telescope turns like a turret. The NexStar 8 GPS is about two and a half generations later than the Ultima 2000. This new version of the C8 incorporates every innovation Celestron has developed for the telescope itself along with every development they have introduced for mounting one: Optical Tube Assembly (the telescope itself) (1) A carbon fiber optical tube. This saves weight but more importantly it reduces the coefficient of thermal expansion between the front and rear of the telescope so it stays in focus as the temperature drops at night. (2) Fastar- The secondary mirror unscrews from the telescope and a special lens assembly goes in its place to turn the telescope into an 8 f/2 (yes a 400 mm focal length) CCD imager. (3) A large 9X50 finder- I ordinarily think of the finder as a sort of big peep sight but this one gives a good enough image to mention. When Jupiter approached the beehive cluster earlier in 2003 the finder showed them together when the telescope couldn’t. (4) Clean-room assembly. I haven’t been able to find one speck of dust in the interior. The glass appears perfect. (5) Fit and finish is beautiful. The tube is a matt finish with clear resin so the carbon fiber is visible- very pretty. I design and build carbon fiber parts for a living- these are nice. Mount: (1) Twin arms with the scope mounted between. This is a new mount and all of the electronics are concealed inside the base and the arms with only the detachable hand controller (2) Twin axis variable rate fine control electric drive system. It’s accurate and when in fine tracking the telescope is so quiet I have to look for the glow of the hand pad to see it is on. This is a very nice feature compared to the RC car sound of the Meade LX200 scopesand their odd crunching sound while tracking. (3) NexStar control (see my other reviews for more- all of them are similar in operation) with the refinement of GPS and an internal magnetic compass so the telescope can resolve its own location the true local time and basic directions without help. It can do this in the alt-azimuth mode or if it is on an equatorial wedge. When set up it can slew to any of 40 000 preprogrammed objects or items you store in its memory. (4) The scope comes with a rugged adjustable tripod. After my experience with the Celestar 8 this stands out. The mount comes with vibration suppression pads (little disks you put under the feet to absorb vibration when the scope is on a hard surface) but I have found there is simply no noticeable vibration time if you set the scope down on a grass lawn. As I mentioned in the Celestar 8 review the way I came across this scope was a little odd. I had seen what looked like a really good deal on the Celestar 8 where you would be in business with a clock drive and the works for $1000. However the tripod on it was too low too wobbly and getting another one was over 65% of the cost difference between that telescope a bare-bones C8 and the $2000 NexStar 8 GPS the fully loaded do-it-all home observatory. So I talked it over with my wife and she pointed out several things: The NexStar could point itself. Even when you know where an object is it takes a while to get to it and this isn’t the point of an evening’s observing. The NexStar is made for doing everything- it’s the nicest version of the optical tube Celestron has ever offered. The Celestar 8 had beautiful optics. No dust and it even had perfect collimation on arrival. It showed the C8s are as good now as they have ever been so I had reason to think the next one would be as good (believe me it took some consideration and a leap of faith to send that tube away). In short the delta in cost came with all the cool stuff there was. I was only going to have one of these so I bit the bullet and called up the folks at Woodland Hills www.telescopes.net and they didn’t have a problem with me upgrading to the other scope. So I carefully boxed up the Celestar 8 and a week later they sent me the NexStar 8. The box which shows up for one of these is big. I mean small refrigerator big. A second box holds the tripod. They are packed like all of Celestron’s other equipment with a box in a box with the hardware in conformal foam. Getting the boxes apart in this scale is a little bit of a trick. But the scope was in there larger than life. I am going to break with some and call this a large scope. Some have said the 8 is the largest of the small scopes but I am going by another criterion here- a small scope is one which goes outside in one piece with its mount. Based on that the largest small scopes are 5 to 6 depending on their design and the 8 SCT is the small end of large scopes. The NexStar 8 has integrated handles for picking it up and moving it easily despite its 40 lb. weight (compared to others with handles seemingly bolted on as an afterthought). The arm away from the hand controller has a handle parallel to the arm and if you lift here the tube and fork assembly will hang sideways balanced on this handle. There is a scoop handle under the hand controller slot which lets you lift the fork assembly (FA) with the base down to go on the tripod. It is much easier to handle than the Celestar 8 was and is easier to carry since the position of the handles lets you carry it with the tube pointed at the base. Three bolts hold the mount base to the tripod. A peg in the middle of the tripod top makes alignment easy. Here is what you do to take the scope outside: First unbolt the fork-tube and put the 3 bolts in your pocket or in a helper’s hand. Lift off the FA and set it on a table where no one can bump it. Pick up the tripod and take it out to the observing area and set it where you will observe from (look up to make sure you are clear of obstructions). Go back and get the FA and set it down on the tripod. There is a step in the center of the base so getting on the peg may take a couple tries. The bolts go in from the bottom but you need to have the base turned the right way for the holes to align. There are protruding foot-like features on the base which go midway between the tripod legs. feel for the hole underneath and have one bolt ready. When you feel it click into the threads only thread the bolt in far enough to hold it in place. If you tighten it down the others will not go in. Loosely thread the second bolt and thread the third and now go around and tighten all of them finger tight. Run the power cord plug it the scope and turn it on. The only difference between this controller and the other like this I reviewed is it comes up with GPS align as the first option. Lock the clutches with the tube pointed down and it goes through the alignment routine itself. The first time is longer since it is finding satellites and also has no true North declination for the internal compass. If you go a long distance you will have the same situation. The compass needs to have a declination from true North and this is setin the Utility menu after you have the scope precision aligned. This takes the precision North the scope has stored on that observing session and compares it to what its internal compass says to get a perfect local declination. The next time you align it it will have a better first guess to start from. Moving it back in at the end of the night is the same process as taking it out. I have found I need to look up and see a really clear looking sky to break this scope out but the image when I do is always beautiful. The mount moves at a top speed of 3° per second so it is a bit slower than the other NexStar mounts which top out around 5° to 6° per second. That said it is still pretty fast. The one thing to remember is it must always be moved by the motors to keep its alignment. The Ultima 2000 had its encoders on its axles so you could push it to a new spot by hand and it would pick up tracking when you let off. This scope will be totally misaligned if you do that and you will need to start over. That said alignment for this scope is easier than any other Nexstar in everyday use. You turn it on tell it to GPS align and wait for it to slew to the first star center it in the finder follow up by centering it in the telescope then do the same for a second star it slews to and you are ready to observe. The tour has a large selection of objects to look at- stars nebulas clusters and galaxies. Planets and the moon only come up on the Planets menu not the tour. Different objects are listed different ways and depending on how advanced an observer you are you can get to them either by what they are a catalog ID (like NGC 1421) or by the tour if it is a famous object like the Sombrero Galaxy. I have not seen all 40 000 objects in its database. In fact I am pretty sure I haven’t seen 10% of that. It will take me a long time to get to to them all but actually the best thing about this is it lets me surf the sky. Yes you heard me say that. I can find M57 in a few minutes. This telescope pops onto the Ring Nebula automatically. The best part is the view it puts forward is very sharp bright and commanding. The telescope came out of collimation and I had ordered a set of Bob’s Knobs which I never installed in the Celestar 8. The Celestar had put out an amazing view of the Orion Nebula with 5 stars in the Trapezium. The new Nexstar on its first night only showed 4. The images of Jupiter and Saturn weren’t as incredibly sharp either. In short I felt a sinking feeling. Then I put the scope onto Betelgeuse near the zenith and looked at the star’s image at 400X. The bull’s eye diffraction pattern was skewed to one side; the scope had been shaken out of collimation in transit and I really should have checked this first. I went back and put in the knobs and tried it out again after collimating the scope the next night. This time it was a different experience The new NexStar was every bit as sharp as the Celestar 8 had been. Compared to other C8s I have seen I would have to rate it as at the high end of capability. The Ultima 2000 scopes were similar in performance and the story is they were screened for good glass. At this point it appears getting free from Tasco (which had bought the previously independent company in 1998) may be the best thing ever to happen to Celestron. This scope has the plusses and minuses any scope with a 2000 mm focal length and 8 aperature will have. First it has a limited field of view. The Pleiades won’t all fit. If you are looking at Double Cluster you need to choose which one you want to look at. On the other hand it really does fairly well on planets compared to wide angle Newtonians. I’d still have to say every serious observer needs to have a good SCT at some point. This is a lot of telescope and for an urban observer it will do a lot. It is also able to go fairly far down in magnitudes so a large number of objects come through nicely. For example the Blue Snowball a blue colored nebula resulting from an exploded star is obvious even in the middle of New Orleans. Saturn and Jupiter are drop-dead gorgeous through this scope. The view of these objects is intoxicating. The belts on Jupiter show their swirls and eddies while its moons are little colored balls. Saturn shows the Cassini division its little moons and the gradients in the rings. The f/6.3 focal reducer stops the focal length to 1280 mm and it can be used with eyepieces up to 32 mm. I can report now it works well and lets the Pleiades and Double Cluster fit in t a field of view. I will be posting a review on this device soon. I have been using a Celestron binocular viewer (#93690 ) with this telescope which splits the image up for two eyepieces so you can look with both eyes. The results are very impressive though I have one friend who does not appear to be able to integrate the images. I wrote a review on it separately. All I can say is it makes a huge improvement in the observing experience with better visible detail and eliminates eye strain. The 8 unlike the 5 SCT does have some mirror shift. This means when you are focusing and reverse directions the image will shift slightly. It is very slight on this scope as it was on the Celestar 8 but is there. to focus it you should move back and forth past focus a couple of times so you see what the image focuses to and then approach from the direction where you are raising the mirror against gravity and stop at focus. It sounds complicated but it isn’t in practice. If you find the mirror shift unacceptable there are add-on refractor type focusers available for these. Tips and Improvements (1) Have a plan before you try to move it. Think through exactly what you are going to do and what order you are going to do it in. Otherwise you can find yourself holding the mount with one hand with it balanced on a knee while trying to get a door open. (2) Make sure the clutches are tight before you start alignment. The position encoders are on the motors so if it doesn’t move with the motors it loses orientation. It can still move some with the clutches off so check. Keep this in mind because you need to loosen the clutches to move it without risking damaging the drive. (3) Wait for the controller to finish a move before punching in new commands. It is possible to make it lose its place if you give it a string of commands while it is moving. The drive on the mount abruptly quiets down as it slows at the end of its slew to a new object and it is easy to think it is done moving when it is actually needs a few more seconds to finish its fine adjustment. Look for the little spinning / icon in the upper right corner of the controller display to disappear before giving it new commands. (4) The telescope doesn’t have a glare shield/ dew cap with it like a refractor. This lightens and shortens the tube but leaves the scope vulnerable to dew forming on the corrector plate. You can spend $30 on one or you can make your own. This works with any scope so I have made the process generic enough to do it with others: Get 3 mm thick black art foam (in 11X17 sheets at craft stores) a hot glue gun and some sticky back velcro tape. Measure the circumference at the viewing end of the telescope. You can also measure the distance across the outside and multiply by Pi 3.14159. You will make a cylinder of the foam to this diameter with a strip of velcro in it so you can open it up and wrap it around the tube for travel (cushion and stowage in one!) For a 5 scope you will want to make 4 panels for an 8 tube I recommend 6. Divide the circumference by the number of panels and then add a half an inch or a centimeter to each one to make a glue land. The glare shield should be a few inches wider than the diameter of the telescope. What you want is to produce a sort of shade so descending dew laden air doesn’t flow across the front of the telescope. The shield also helps by blocking off-axis light from shining in and dulling the image. Draw your pattern right on the foam with a pencil so the glue lands you have in mind will be visible and help you align the pieces. Make one longer than the rest by another centimeter or half an inch to allow you to adjust the fit with the velcro. Glue the panels on top of each other with hot glue in a stair step pattern. Leave the long panel to be the Bottom step. Stick the velcro to the short end on the outside and wrap the glare shield around the telescope tube. Attach the other side of the sticky velcro where it touches down and voila- you have a flexible glare shield for under $2. To use it just put it together and then slip it over the front of the telescope by canting it and getting it started on one edge then working around the tube. It will be a little stretchy and this is what keeps it on. Use the back edge of the metal corrector cell as a guide to get it evened up. It is light so you won’t change the balance. If you wrap it around the optical tube to store it you will find it it stays nice and round and acts as a bumper while moving the telescope. If you want you can make it out of a colored version of the foam but you will need to paint the interior side black. I suggest flat black acrylic paint. Give it at least a week to dry in a warm place before you put it on the telescope. (5) No direct battery provision- the scope comes with an AC power adapter but using it away from a plug requires you to get either a car adapter or a battery pack. (6) Get a set of Bob’s Knobs (www.bobsknobs.com). They make collimating the scope easy and the performance just isn’t at its best until you get the collimation perfect. Simply put the difference between seeing 4 stars and seeing 5 (ups- 6) in the Trapezium in Orion was recollimating the scope. It is worth the trouble. Summary This product is one of the most flexible observing devices ever made. For any task there are accessories available from Celestron or other vendors to do it. In essence it is the culmination of 35 years of trying to build the one telescope to have if you only had one. It is even handsome in the living room. With its tripod set to a comfortable viewing height mine stands 66 tall so it is pretty imposing. It shines under the night sky it guides itself and the images are beautiful. For about this much money you can get a high end refractor which will produce similar images on planets but will be dimmer on deep space objects and will come with no mount or anything else. You could alternatively get a Dobsonian telescope with a huge mirror and a very simple mount. It will be harder to transport and can find nothing on its own but will excel on dim objects. I’m not sure if this should be a first telescope but if it is it can do it all. Perhaps the best thing I can say about the NexStar 8 GPS is it has shown a jack of all trades doesn’t mean master of none. UPDATE 8/30/03: The Mars 2003 Star Party On the night of August 27th Mars made its closest approach to Earth. The astronomy club I am a member of the Pontchartrain Astronomy Society sponsored a public star party at the planetarium and observatory in Kenner (west of New Orleans). Quite a few of us decided to bring scopes oout so people could get a look (this was unpaid- none of us asked for or were compensated in any way). My wife and I brought two telescopes- a little C90 and the NexStar 8GPS. Where we set up with the other club members there were large floodlights shining directly on us. Mars would be the only observing object so this didn’t hurt matters that much since the foam glare shield was long enough to keep the light from shining into the front of the telescope. At 7:30PM we had everything put together and had a moment to get a sandwich and a drink. These would be the last still moments for some time. I got the telescope lined up and started tracking. My wife ran the C90 about 20 feet away. Also present were a Meade 10 scope on a Losmandy mount which had a webcam and the live image diaplayed on a notebook computer. A Televue 102 4 scope Orion 100mm and even a Takahashi FSQ-106 refractor also came. Reflectors included a home made 6 Newtonian and another Celestron SCT. The observatory is equipped with a 14 Celestron SCT. A few people came to look and I showed them how to look into the binocular viewer which I started out with 2 20mm eyepieces about 125X with Mars near the horizon. The image boiled from heat near the ground but the ice cap and the dark areas were visible. I placed myself between the flood light and the observer so they could see. A few more people walked up and looked. A few minutes later there was a crowd. I turned around and had a moment of shock when I found a line of about 30 people extending into the street. What ensued was an experience I really wasn’t prepared for but it was definitely a good one. I estimate about 800 people looked through that telescope that night. By 9:30 the seeing was better as Mars pulled away from the horizon. I put a 2X apochromatic barlow in to boost power to 250X. Mars now showed its sandy-orange-red color clearly and the ice cap showed its comma shape. It was very beautiful. Some very nice people came back and brought us water bottles when they saw we couldn’t leave the telescopes. The seeing was actually only fair as mist and clouds rolled over. However we were lucky since it was just water vapor instead of ice crystals so the image just became dim instead of blurred. Mars itself periodically disappeared to the naked eye. By around 11:00 it had been quite an evening. I noticed some of the people were repeats. I asked one about it and he said I looked through all of them- this is the best view here so I came back. That was a bit of a surprise considering the competition. But perhaps it shouldn’t have been. The people were all very nice. I was thinking only a dozen or so would stop by. It seems a lot of people really like Mars. This was really a neat experience all around. The NexStar 8GPS has really come into its own and I see I will be using it quite a bit more in the future (Saturn and Jupiter are coming up for Fall viewing!). After the views I had of Mars this time around I will be looking again in 2020. Mars is still in the neighborhood so I will keep looking over the next few months. Updated usage tip: I have a work bench in the garage I have started using as a telescope staging point. What I do is take the NexStar off of its tripod indoors and take it out to reach the outdoor temperature when it looks like the seeing will be good that evening. Here in New Orleans your telescope will be ruined by the humidity if you leave it out full time. This way it is possible to keep it clean and dry but not have to wait for it to warm up or cool off when going out to observe. UPDATE 12/06/03: The NexStar in Winter I have been doing more observing as the Winter stars have risen again. My favorite constellation is Orion and with its return I have started experimenting with photographing with the NexStar8 GPS. This is when the first problem I have had with it manifested itself. While tracking an object the telescope would periodically jump in the altitude direction and then slowly return to the object. I called up Celestron about this and they said it was a known fault and I could either (A) get the interface cables and run a windows program to update it or (B) I could send it to them to be reprogrammed at no charge other than shipping. Strangely enough the cable is $30 and the shipping there and back was about $12. So I followed the instructions to unbolt the side of the left hand fork and found inside the controller board bolted to the arm with five bundles of cables plugged into it. I unplugged the cables removed the board and sent it away. Celestron upgraded the card and now the telescope is back in business and all is as it should be. The scope has even managed to be quieter than I remembered it. I have been observing the winter sky and learned a few more things about the telescope. Perhaps the most important of these is it becomes an even more flexible instrument with the focal reducer added- the Pleiades can all be seen at the same time for example. And I have learned I was wrong about something after I returned to the Trapezium in the Orion Nebula. I spent some time looking around the four stars with the dim fifth and looked for the sixth and to my surprise found it. Saturn is getting closer and rising earlier. I’ll post more as I get a chance to do more in the cold clear skies of this time of year.Recommended:Yes
18th
Celestron NexStar 5i (300 x 127mm) Telescope
(No Ratings Yet) Loading ...Posted by John under Telescopes
The Biggest of The Small Scopes Pros: Compact light mobile good optical performance cool package deals commonCons: Does nothing without power tube not removableThe Bottom Line: For a beginner this will give a lot of capability to do a lot of things from the get go. The NexStar 5i is the latest incarnation of Celestron’s 5 Schmidt Cassegrain astronomical telescope (SCT). It now comes with more capabilities than ever before in a small tracking package. In my view this is very much a worthy successor to this line of unparalleled telescopes. More information on telescopes and choosing one for yourself is in my review on Picking a Telescope. To help organize this review I have divided it into the following sections: Background Description Observations Tips/Notes Summ