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My Older 11" SCT (C11 Ultima)

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My Older 11” SCT (C11 Ultima)

By Tye Rausch
Market Value Price: $1500 - $3000
A great hobby purchase! Available through astronomy clubs, want ads, & eBay (careful!)

Operative words in this title: “(Older)” and “SCT.” Why? Let’s face it…budgetary concerns and portability. If it were affordable and portable, I’d want the Large Binocular Telescope! SCT’s are short and compact for their light gathering ability. Most of us would love to own a fluorite refractor, but again, reality is:

Money, Money, and Money!

Ah, yes – those three most important things when considering a hobby purchase while maintaining other payments and in many cases domestic harmony… I purchased my Celestron Ultima 11” for $1100. “That thing isn’t a go-to scope, is it?” you ask. Answer: “11-inch for $1100.” Yes, the great deals are out there if you don’t insist on “bleeding edge” technology!
Knowing everything technical about a telescope, while important, has never been my reason for owning one. I love to go to “big-sky” places, gaze for hours at the heavens, and take deep space prime-focus pictures. If you can identify with these motives, you should consider the bang-for-your-buck and portability of a larger (8” to 12” – but not 20”, not portable) SCT, like my Celestron Ultima 11”.

Working Within the Features of the C11 Ultima SCT

Manufactured about the mid ‘90s, this scope has reasonable “Astrobright” lens coatings, and the light-gathering capability of 1,593 human eyes. It has a decent worm gear clock drive on a wedge mount. The tripod is massive and sturdy. The tripod-top pivot RA adjustment for polar aligning is clunky and has too much play, which makes it easy to bump out of polar alignment. The rear cell easily adapts to both 1.25” and 2” visual backs (I often switch several times a night between the two, depending on what I am doing). T-ring adapters are available and affordable for most cameras. Various filters are readily available. Drive motors and the like are getting harder to find, but, of course, the OTA could be put on a modern mount for a price.

While I have heard others complain about the cumbersome older C11’s, I personally have toted mine to the south-facing precipice of Mt. Graham at 9000 feet, (southern AZ, higher than the LBT location) and all over the deserts of the southwest. I try to arrive a little before sunset, and take my time setting up, so polar alignment goes easily as soon as the North Star and a few other major stars are visible. This scope weighs about 140 lbs with all the gear, and I weigh about 150 lbs. I am neither big nor young. You needn’t be as ambitious as I am to enjoy great observing. Packed creatively (sometimes in two trips) it’s a case of “mind over matter” – if you don’t mind, it doesn’t matter!

Miscellaneous Challenges and How I Deal With Them:
Everybody’s first question is always “Aren’t those old fork-mounted scope too shaky to take pictures?” True, it ain’t a Losmandy mount, which necessitates a few precautions:
  1. If you intend to take pictures, set up with a remote shutter release and don’t touch the scope. Avoid windy conditions. (Say… that’s the same for any scope!) Be sure to have correct counter-weighting.
  2. Make sure you give polar alignment you best shot, and use the old “PEC” (Periodic Error Correction) recording function to take as much wobble out of the worm drive’s action as possible. Polar alignment is critical on this model, because without a declination drive motor, your RA drive buttons take aberrations and anomalies out of RA motion only. This puts a practical limit of only about 2.5 minutes on exposures, but in many cases this is enough. An after-market declination drive is a good investment for proper guiding, as Celestron has ceased production on their dec drive for this model.
  3. Probably the single most important purchase you can make for the C11 is a Reducer/Corrector, which may be purchased for @ $130. Why? Because it flattens the fov and lowers that f-stop to f6.3 (lower for some Reducer/Correctors, but the lower ones are generally not as suitable for visual observing.) If you have a potentially shaky scope you can make reasonable exposures in a fraction of the time!
  4. Use a digital camera or CCD imaging system. You can discard non-focused or jittery images on the spot, and just keep persistently plugging away until you need more coffee or the sun comes up.

The Ultima tends to have sticky declination bearings that jump 1500 when you are trying to “star hop”. With the OTA off, take the bearing covers off and lube with graphite. Then, when star hopping, be sure to pull on the OTA mounted loop and not your eyepiece or camera!

The large aluminum forks definitely are an inconvenience when polar aligning or viewing the north sky. You’ll need patience, flexibility, and definitely a 900 star diagonal and right angle prism on your finder scope. I use an 8x50 finder with a right angle eyepiece.

It is difficult to focus properly with a nebula filter and camera in place. Cheap solution: focus on the moon or Jupiter and its moons. Good solution: a filter mount that rotates out of the way without changing focus. To the left is a typical setup I use for this SCT. It includes (left to right) a camera t-ring, a radial guider and micro-guide eyepiece, a nebula filter, and an f6.3 reducer / corrector. I use a Canon EOS R300 camera.

So, Can a fork-mounted SCT Perform?
That really depends on you, the user. With the above setup, it is possible to take some great images if you are patient and tenacious! This older scope has taken respectable images of quite a few celestial objects. Some (Photoshop levels enhanced) examples are:

Despite numerous limitations and challenges, my experience with this scope has been a delightful experience and very rewarding. In general, the C11 Ultima SCT can be a terrific value for the amateur astronomer who creatively works with his/her instrument.


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