Last updated on
4/11/
2006

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What's So Special About a U2K?

Most experienced amateur astronomers agree that the best telescope is the one you will actually use, and use often. If you donít have dark skies at your house or you donít have the room to build a permanent observatory you will need to transport your scope, if only from your house to your back-yard.  Thus your scope needs to be light enough and compact enough, that setting it up is not so much a chore that after a while you stop using it - a common fate of heavy scopes.  If you want to do astrophotography you also need some light-gathering power and a very stable mount. Considering these criteria a good choice is an 8Ē GoTo catadioptric scope with a good, rigid mount.  Assuming you might want to do astrophotography the most popular choices have been the Celestron U2K and the Meade 8Ē LX200 . (Both Celestron and Meade offer scopes that are intended only for visual observing but not astrophotography, as noted in the Telescope Basics page.)

Many of us amateur astronomers chose the U2K for a number of reasons:

Weight Without their tripods, the U2K is 31 pounds and the LX200 is 41 pounds.  For most people, 41 pounds is starting to get difficult to manage. Keep in mind that placing the scope on an equatorial wedge means holding it and supporting it at an angle while you mount it on the wedge, and youíll probably be doing this without anyone elseís help. Try this: go to your local supermarket and hold three ten-pound bags of flour out in front of you.  Then hold four of those bags. Tilt them and move them around.  If the difference doesnít matter to you, then the weight of the LX200 will be OK for you. Note that very light weight isnít necessarily good either - the mount needs to be rigid and vibration-free enough to support astrophotography. Many GoTo scopes do not; the U2K does, as you can see if you go to some of the U2K astrophotography pages on my Links page.

Fastar The U2K (as well as Celestron C8ís, the CM-1400, and the new NexStar 8Ē and 11Ē GPS scopes) has a Fastar option which, when used with a CCD camera, allows you to convert the scope into a fast (f/2) wide-field Schmidt Camera.  This is a major advantage when photographing deep sky objects. A Schmidt Camera is probably the ultimate instrument for deep-sky astrophotography, but the U2K with the Fastar option and a CCD camera will get you pretty close, for some $22,000 less.  See the Fastar & Pixcel page on this site for more information.

Noise The LX200 is significantly louder when it slews to a new object (although not when itís tracking an object).

Aiming The clutch system in the U2K is designed so that you can manually aim the scope at a different object while itís tracking - the clutches are designed to slip without damage. With the LX200 you need to disengage the tracking motors to aim it manually, and when you do this the LX200 loses its positioning information (because the optical encoder was disconnected from the drive). And you will find that as you gain experience in locating stellar objects you will use the GoTo function less often (typically for hard-to-find deep sky objects), and being required to use a computer to bring a plainly-visible Jupiter into your eyepiece is annoying. The GoTo function in computerized scopes is a great tool that you will often, but not always, use.

Note that the Celestron clutch design has caused Meade and Celestron NexStar owners to claim that the U2K is unduly sensitive to being balanced as you hang weight (a camera, etc.) on the back of the scope. It is true that the U2K will immediately notify you that it is unbalanced, when the heavier end moves down.  The funny thing about the argument is that all scopes need to be balanced to track accurately.  Unfortunately, Meade and Celestron NexStar scopes donít notify their owners when theyíre unbalanced, leading to tracking errors and the eventual possibility of worn clutches or drive motors if the imbalance is severe and continual.

Hand Controller The U2Kís hand controller uses a relatively old-fashioned red LED display rather than the more modern LCD display. Whereas the LCD display can be made larger and thus present more information at a glance, LCDs are susceptible to dimming out and becoming unreadable when they get very cold - LEDs do not. So the U2Kís hand controller does not require a warming unit when used in very cold weather.
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Unfortunately Celestron has discontinued the U2K, replacing it with the 8Ē and 11Ē NexStar GPS scopes.  These scopes sit at around the same price point as the U2K did, and they do use the FasStar system.  But the NexStars donít allow you to manually aim the scope like the U2K did.  Note that the 11Ē NexStar GPS is a lot heavier than the U2K, but you do receive almost twice as much light-gathering power in return for the extra weight.  Nevertheless if you can still find a U2K for sale it is highly recommended, even by Celestron employees.

Yahoo Groups include a few groups that focus on SCT scopes, especially the SCT-User and the Ultima2000 Groups. Over a few years these groups have included messages that offer specific advice for the U2K. I have accumulated those specific tips into a single word-processing file that is current as of the end of October, 2003. It is available here for your download as a zipped RTF (Rich-Text Format) file, which is a word-processor-independent format:

U2K Tips from Yahoo Groups 10-2003.zip

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