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Old 25-01-2010, 10:49 PM
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rat156
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Join Date: Aug 2005
Location: Melbourne
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Quote:
Originally Posted by Peter Ward View Post
I disagree for various reasons....

To carry the short FL argument to its absurd conclusion you only need look here http://www.atscope.com.au/BRO/gallery38ro.html
(a few hundred mm versus about 6 metres FL)
Yes, Peter that is absurd. I should have put a disclaimer in there that you still have to be sampling at about 1/2 you're seeing, up to about 2"/pixel seems to work well, so I could easily shoot at 800mm rather than the 1600 I shoot at. The only thing that will suffer is image scale.

Quote:
Originally Posted by Peter Ward View Post
To get truly high resolution, you really do need focal length.

Sure to get an OK looking image, short FL's are very user friendly. Seeing. mountings, tracking errors etc. are all masked with modest conditions and equipment.

Small pixels are not without their problems...scattering and shallow well capacities don't help.

High-res deep sky however is a challenge (for me at least)...with good seeing more often than not playing a pivotal role.
To get high resolution you need to satisfy Nyquist. If your seeing is exceptional, you'll get better results as long as you're sampling rate is high enough. If you've got a telescope in outer space then the resolution is defined by your optics, the mount is also rather expensive and the installation astronomical, possibly out of an airline pilot's range even...

Cheers
Stuart
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