Celestron Ultima 11

Schmidt-Cassegrain Telescope

I joined the Central Coast Astronomical Society (CCAS) in February 2000, never having been involved in astronomy work before.  Within a month I volunteered to create, host and maintain a website for the CCAS.  That has turned into a significant long-term project that I really enjoy.  I have attended numerous star parties since then, using other astronomer's telescopes, and have really developed an interest in studying the cosmos, even to the point of occasionally volunteering to host star parties and presentations for school classes using a CCAS telescope.  Very unexpectedly, in February 2001 I became CCAS President, so now I REALLY have to become familiar with telescopes and the skies above us.

I have been very interested in someday obtaining a nice scope.  Much to my surprise, in December 2000 my father was extremely kind in supporting my desire to become seriously involved in astronomy by supporting my purchase of a previously owned 1995 Celestron Ultima 11 telescope.  A fellow astronomer in the area was selling his which was just what I was looking for.  Here are some specifications:

2800mm focal length, f10
1200 times the light gathering power of the human eye
Rubber coated tripod
Wedge and fork mount
Motor drive operating on a 9-volt battery
Periodic Error Correction and operates at Sidereal, Lunar,  Solar and "King" Rates
Hand controller for Right Ascension
8x50 Illuminated Reticle finder scope
Telrad finder
Meade 32mm wide angle (2") eyepiece
Celestron Plossl 26mm (1 1/4") eyepiece
Meade 13.8mm super wide angle  (1 1/4") eyepiece
Meade 8.8mm super wide angle  (1 1/4" or 2") eyepiece
1 1/4" and 2" star diagonals
Reducer - Corrector F6.3
Camera adaptor
Vibration suppression pads

see below for an expanded description from Company Seven

Here is my astronomical toy.  Click on the photo for a larger image.

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Celestron Ultima 11 (279mm) Schmidt-Cassegrain Telescope

by Company Seven

The Celestron Ultima 11 Schmidt-Cassegrain Telescope (SCT), introduced in October of 1995, replaced the older Ultima 11 PEC telescope with a redesigned fork mount resulting in lower weight for better one man transportability. This telescope is geared for ease of set up and use, and for astrophotography while also retaining the traditional very good deep sky and planet observing characteristics of the C-11. We consider the C-11 optics on either the German equatorial or fork mount as offered here as offering the best balance of aperture and portability possible for the person of average physical stature.

This telescope incorporates an up-dated design of 11" (279mm) aperture with a nominal focal length of 2840mm resulting in an f10 system. This increase in aperture over a comparable 8" telescope results in a significant light gathering power 1.9X that of an 8" telescope, and still the telescope remains manageable by one person of average stature. This telescope effectively offers about 1200X the light gathering power of the unaided human eye; this is greater than a good quality 10" f6 Newtonian (at about 1100x) that would be about 60" long and weigh far more on its associated equatorial mount than any Celestron 11" telescope.

With this focal length one will need an optional telecompressor (focal length reducing) lens in order to take a photograph of the entire full moon on to a standard 35mm film format. And at prime focus magnification as low as 52X covering 1 degree actual field of view are practical. However, with an optional telecompressor lens the field of view can be increased. And as with all Celestron SCT's these are really made in the U.S.A.!

A rugged, fork mount with sand cast drive base makes viewing and astrophotography possible - if the telescope is in a shelter or very calm environment. It has streamlined fork tines with Declination setting circles, with an adjustable clutched tangent arm Declination manual control, and an extra large polar shaft integrally cast into the base. This base includes precision preloaded polar axis ball bearings. The base also incorporates a clutched manual control for Right Ascension.

Some of the Ultima 11 features (similar to the older Ultima 8" and 11" PEC telescopes): a totally cordless DC Servo quartz drive system with hand controller. The system electronics incorporate PEC (Periodic Error Correction) with an easy 4 minute recording cycle, highly accurate worm gear drive, four tracking rates including King, sidereal, lunar and solar and a slewing speed of 400% sidereal rate. In a Sky & Telescope review of 8" Schmidt-Cassegrains, it was noted, "the Ultima 8's drive error was the least I have ever seen in a mass-market telescope." Astronomy Magazine said of the drive, "a textbook straight line" and "the PEC is impressive. It worked better than advertised."

The power-efficient Ultima 11 runs off a 9V alkaline battery. AC or 12V operation of the Ultima 11 is possible with optional adapters. In addition, it can be used in either the Northern or Southern Hemisphere.

A Sky & Telescope review of the Ultima 8 summarized it nicely saying, "Which telescope would I buy? ... For me the choice was easy....A drive that requires no external cords or power supply makes a perfect instrument to take along for casual observing. Coupled with these features are optics rated as the most consistent."

Ergonomic user-friendly operation is the trademark of the Ultima 11. It was designed with functional use foremost. Convenient carrying handles are provided on the fork tines and the rear cell for ease of handling and transport. The focus knob and all manual controls are scaled for use even when wearing gloves. And the focuser accepts an optional a micrometer with a digital display to aid those who wish to employ the system for astrophotography and CCD imaging.

Included is a heavy duty wedge with a deluxe latitude adjuster, latitude scale and accessory tray. The adjustable height, metal adjustable height field tripod is also furnished as standard equipment.

Standard accessories include: 7 x 50mm Finderscope (with integral Polar Alignment reticle), Prism Star Diagonal 1-1/4", Visual Accessory Back 1-1/4", and a 26mm Plossl Eyepiece 1-1/4" (108x). Weight is 80 lbs.