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Subject: RE: [M]: Telescope Selection Help
From: Michael Hart
Reply To: mapug@shore.net
Date: Tue Nov 26 01:12:52 1996
Wade Holguin replied on 11/4/96 to a "Celestron or Meade" question:
>The Utima 2000 will do all the CCD work you mentioned your LX-200 can do,
>including high precision pointing and tracking on the order of 19 arcseconds
19 arc seconds, if correct, would be extremely good pointing accuracy. 19
arc seconds tracking periodic error would be a problem for me. The original
Ultima resolved tracking problems with the use of a Beyers geartrain and PEC.
The first Ultima 2000 used a friction drive which negated the need for the Beyers
geartrain and PEC, but was recalled shortly after it's release a couple of years ago.
The LX-200 uses worm mounted encoders that effectively increases the number
of steps to enable an advertised 2 arc minute pointing accuracy. Adding the
64,000 object database enables adding many local star coordinates and increases
pointing accuracy to an advertised 1 arc second. It would seem the Ultima
2000 direct mounted 8192 step encoders would limit pointing accuracy at best to
to a very respectable 2.63 arc minutes in standard resolution and the 10,000 object database would be a limiting factor in achieving ultimate pointing accuracy when
using a local star. The LX-200 is pretty forgiving with respect to imbalance that
is frequently produced by CCDs and cameras.
I have seen no Celestron claims of 19 arc second pointing accuracy or 19 arc second
periodic error to date.
>when using Enhanced Encoder Resolution (EER). Standard resolution of the
>encoders is 2.5 arcminutes. You can also use the "Relative" command so that
>the scope will point to a star within 5 deg of the desired object. You
>center the star and the computer uses it as a reference to get to your
>desired object more accurately. I've owned an LX-200 and now have the Ultima
>2000. Todd Gross on this list also has experience with both scopes.
On August 28, 1996 Todd Gross wrote:
>>As posted on sci.astro.amateur:
>>Ok... your personal guinea pig here.
>>I received the Celestron Ultima 2000 on Friday, and gave it a quick test run
>>or two over the weekend. Comparing it to an 8" or 10" Lx200, here are a few
>>first impressions.
>>1. The Ultima 2000 is much, much quieter, almost whisper quiet
>>2. The tracking appears to be somewhat less precise, have to double check
>>3. Pointing accuracy does not appear to be as good. Saturn was consistently
>>off, objects at the zenith were harder to place in eyepiece. Overall pointing
>>accuracy though still acceptable to very good with most objects falling less
>>than 15 arc minutes off in either direction of center.
>>4. The biggest drawback seems to be the need to balance the scope critically,
>>with their rather well thought out, but inconvenient weight system. This "may"
>>have been what held this scope up from coming out.
>>5. Unlike the LX200, this scope is conveniently moved MANUALLY most often
>>without it losing it's knowledge of where it is pointing. The hand controller
>>is used more for centering objects, not for slewing around. This is a plus.
>>6. The hand controller is more complicated to use, but the menus are laid out
>>fairly logically. However, it is small, and was easily velcroed to the tripod.
>>7. The manual is not that great.. worse than the LX200 which is not that great.
>>8. OPTICALLY>> The star test (I am no expert in this) was not that great out
>>of focus, but in focus images were quite good - very crisp Jupiter and Saturn
>>views despite the scope being slightly out of alignment! Cassini division
>>visible.. Great red spot clearly seen along with well defined bands and
>>festoons on Jupiter. Color was very evident too.
>>9. The FINDER is better than the LX200 finder by a long shot.. it is a reticle
>>finder, ready for an illuminator
>>10. The WEIGHT of the system is far less than the LX200. The 8" scope PLUS
>>tripod can be easily moved around the lawn w/o a wheely bar, etc.
>>11. It DOES have it's own version of the LX200 High Precision Pointing
>>..although I didn't try it
>>12. There is a slight azimuth wobble back forth, as opposed to a slight dec
>>wobble on the LX200
>>13. The one-star alignment instructions appear to be missing.
>>14. The scope does not know the time, so it cannot do a "no-star" alignment as
>>you can on the LX200, meaning on the LX200 you can do a quick and dirty point
>>on power up.. not possible here.
>>15. It does not have the moon, in it's database..but it does have the sun. Now
>>that is nice.. but I would hate to move to the sun by mistake
>>16. The unit RUNS ON AA batteries!!! (really works)
>>17. As mentioned, the Ultima 2000 retains it's sky orientation at all times,
>>even if moved by hand.
>>18. There is a "warp" value (like on the NGCMAX) that tells you if your second
>>star alignment is not adequate, when pointing to the second star of the
>>alignment. (then you would have to do the alignment over)
>>19. Scope looks like it would be unstable. . but actually is about as stable
>>as a 10" lx200, not as stable as an 8" though
>>20. Scope is a nice slick, grey color, but appears a bit more "toy-ish" than
>>the LX200 at first glance. There are less plug receptacles on the base, but I
>>believe it has the necessary CCD and computer interfaces.
>>21. Tripod seems somewhat better than the LX200 8/10" ones.. nice rubberized,
>>etc.
>>If anyone else has an Ultima 2000, I would like to invite you to join the
>>Celestron User mail list so we can get the ball rolling.
>>Thanks! - Todd
>>_________________________________
>>BOSTON TV METEOROLOGIST TODD GROSS
>>Weather/Astronomy Home Page: http://www.weatherman.com
>>Administrator, Meade Advanced Product User Group: mapug@shore.net
>>Administrator, New England Weather Observer Mail List: wxobs-sne@shore.net
>>IRC Channel Operator: #Weather (Undernet)
>>Originator of the NE.WEATHER newsgroup
>>_________________________________
>>Email: toddg@weatherman.com Work Phone# (617)725-0777
>Good luck in your decision.
>Regards,
>Wade Holguin
Since this is a Meade forum, I just wanted to keep everything in perspective.
By the way, I like the new Celestron PixCel 255 advertisement with the happy
spouse. Now, if a novice can really get that image of M-51 in "no time" to
less than one hour experience without "...years of practice, excellent conditions
and lots of patience" from an unguided 8" SCT on a Wedgpod in their backyard
with a neighbor's porch light illuminating the area, my spouse would be
happy, too!
I have been devoting all my spare time the last two weeks in the permanent
mounting of my 12" LX200 in a private observatory at a dark sky site some
35 miles away from city lights.
Michael Hart
mhart@netexpress.net