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Optoelectronics, Optics, Lights and Lasers > The Science of Light > Optics > 

What are the benefits of the Schmidt Newtonian reflector? if any.?

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Author Topic: What are the benefits of the Schmidt Newtonian reflector? if any.?  (Read 263 times)
nobody
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« on: June 20, 2011, 01:48:03 AM »
Note;ie; Photography versus general observing.
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blobrana
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« Reply #1 on: June 20, 2011, 03:01:41 PM »
Easy to build.
a spherical mirror is used with a Schmidt corrector plate, instead of a parabolic mirror..and no "spider" is needed.

"In this telescope design a spherical primary mirror is combined with a Schmidt corrector plate, making system that has less spherical aberration (coma) than a reflecting telescope with a parabolic mirror. "
"Schmidt–Newtonian telescopes offer images with less coma than Newtonian telescopes of the same focal ratio (usually about half). "
http://en.wikipedia.org/wiki/Schmidt%E2%80%93Newton_telescope

Ie this can make for very 'fast' telescopes; a f4 focal length (or faster) can make for a well suited astrophotography telescope.

For visual observing this will provide stunning 'rich field'  views...
The only bad side in short focal lengths is that you may have to spend money on a quality 'barlow lens' for high magnification viewing (ie planets, double stars etc)
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Larry454
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« Reply #2 on: June 20, 2011, 05:05:00 PM »
It's cheaper. I disagree with the idea that you can manufacture a short focal length scope with a spherical mirror with less coma / aberration than the classical designs with a parabolic mirror. The short focal length means shorter exposure times for astrophotography, but I think you will sacrifice optical quality, so the advantage is dubious at best. So, photographically at least, you would be going cheap, and that's not the path to success in that particular avocation.

I submit that it is not the path to success in any avocation - or vocation. The visual observing compromises are related to the photographic ones. The differences may not be as noticeable, but why make that compromise when you can save up and buy a quality Schmidt Cassegrain or a big Dob?
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tlbs101
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« Reply #3 on: June 20, 2011, 05:34:13 PM »
I had a short SM once.  It was a piece of crap, so I replaced the main mirror with a parabolic mirror of approximately the same focal length (and I re-did the optical tube) and got rid of the corrector.... now it's much better.

Now, I use the spherical mirror as "show and tell" for teaching astronomy classes.

.
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