SCT for the high-power crowd?

Maybe someone with ties to the "industry" can answer a question for me. Why are there no SCT's designed for high resolution/high contrast observing? The cost of a 10 inch MAK or Refractor is well beyond the financial abilities of the people I associate with yet I find this size of telescope to be excellent when you balance the size of the scope against high power image brightness, detail, and average seeing conditions. A 10" cooled high definition SCT produced by Celestron or Meade should be affordable to all who desire a medium cost, large, high power instrument.

Forget the computerized bells and whistles which can break or fail. Just an affordable pure high performance instrument on a nice GEM. Yeah, I know I'm old school and probably out in the twilight zone but, for me, there is something special about observational simplicity.

The image is a "paper" SCT telescope that I have been playing around with off and on for a few years. It has a 26% secondary obstruction, 100% illumination to 1/4 of a degree field of view. Image contrast should be equal to a 185mm APO and the small relative obstruction would make the instrument less sensitive to seeing compared to "standard" SCT's. At F/14 multi-element eyepieces are not needed and longer focal length eyepieces would render high powers with good eye relief. Hey GSO, care to make a lunar/planetary Schmidt? I would buy one 8)

Keith

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Keith: I really don't know that answer to but I do that when I have seen the topic tossed about it was suggested that a high quality SCT would cost as much to produce as any other design of similar quality. As I recall from a discussion several years ago on S.A.A. some thought a premium 8 inch SCT would be around $5000 but with the ACFs, well maybe it would be cheaper. Why exactly would a high quality SCT be cheaper to produce than a high quality MAK?

I personally think though that when one is looking for a high performance "non-refractor", the choice most often points to a Newtonian because premium quality optics as well as individually chosen optical parameters make high quality scope affordable and practical.

Jon

Seems like a great idea. But I expect it will be
difficult for them to keep the price in the "medium cost"
range, and provide an interesting level of optical
quality. But if they can, I'll take two.

Well, there was the f/12 Takahashi TSC-225...

"In 1989 Takahashi introduced their famous TSC-225: a 225mm Schmidt-Cassegrain with innovations such as 10 baffles in the baffle tube and a rear cell fan for cooling of the optics. The 225 used white German optical glass for its corrector plate."

http://www.takahashiamerica.com/catalog/TAK_about.php

http://www.astrosurf.com/sogorb/takahashi/takahashi_tsc.html

http://excelsis.com/1.0/entry.php?sectionid=12&entryid=300

I've only seen one of these superior SCTs in all my years as an amateur astronomer.

Dave Mitsky

Keith Lawson said:

Maybe someone with ties to the "industry" can answer a question for me. Why are there no SCT's designed for high resolution/high contrast observing?

I disagree with your premise. A modern well-collimated SCT is quite capable of high power performance--assuming you consider 500x and above "high power." The catch? Many folks _still_ don't collimate their SCTs correctrly.

Over the years many 8" MCTs (Intes-micro, AP, TEC) and one SCT (Takahashi) have been available that meet your criteria. Expect to pay $4K to $15K for the view.

Good, fast, cheap, pick any two.

While I recognize this is not an "SCT", Bob Royce is making a limited number of 10" F/20 Dall-Kirkham reflectors specialized for lunar, planetary and doubles. I ordered one of the initial five prototypes and have to say it was a great decision. The scope, #3, is easy to set up, a snap to collimate in the daylight (can you say that about a cat?) and when the seeing is good it puts up stunning visual images. It is not inexpensive but for such a superbly crafted instrument with conical mirror, built in cooling fan, a two-speed Moonlight focuser, curved diffraction-free spider and 25% CO I would not expect it to be. Its 5000mm focal length lets simple eyepieces shine. When the better skies of Fall and Winter arrive, I plan to try the Zeiss 10mm monocentric. Best planetary eyepiece I have ever used and a fitting choice for Bob's scope!

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Why restrict your search to an SCT. Perhaps you would like a Maksutov or a Dall Kirkham.....

How about a Gladius for a high quality, high magnification view?

http://www.lazzarotti-optics.com/main.html

Alex

Another possibility would be a used 10" f/20 or 8" f/15.5 Mak-Cass by TEC. Same goals as your design - small obstruction and generous focal length.

Keith,

You mean like this? 1965 Celestron Pacific C10, 10" f15, 27% obstruction.

Cool down is a bear but optics are SWEET!

Dave

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