Old 25-05-2011, 04:44 PM
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Satchmo (Mark)
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Join Date: Dec 2005
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Paul - We are not in disagreement , and I acknowledge all your points about thermal management.

My points and observations all assume that you have good thermal management- I'm talking about the nature of seeing 'cells' in relation to aperture and the aesthetics of different kinds of seeing. No amount of thermal management can give you a sharp steady view in a large telescope if the wavefront is only good for a crisp `visual' view in a 6" aperture ( and here I mean a clear visible airy pattern that is just moving around slowly ) .

Originally Posted by Paul Haese View Post
No Mark I am suggesting that without thermal management how can you possibly know what the seeing is actually like. Having good thermal management will not give you good seeing, but it will allow you to determine what the seeing actually is like.

I will see if I can get hold of a DIM and test this theory thoroughly by testing the seeing via dim and image before and after cooling. That way the dim measurements can confirm what the seeing was at each point, so that the argument cannot be made that the seeing changed rapidly.

I am also talking about visual use too. A thoroughly cooled scope will give better views than a naturally cooled scope. Stick it outside and using a fan for two or so hours is not going to cut the mustard. There are a lot of us now that have the definitive proof of this. When the seeing is good and the mirror is at ambient you get steady views for minutes at a time, not just fleeting moments. At high resolution this can also be for 10-30 seconds at a time.

edit BTW the studies you are talking about are suggesting that seeing at each locality supports a particular size telescope. Therefore it is the seeing at the location which is the determinative factor and not the scope.
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