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There are a couple of parts that caught my attention - none of the maths, that's too hard these days :-)
- Depending on the seeing, there is an "ideal" mirror size that will maximise your resolution and minimise the effects of turbulence. It seems to be about 7 x the size of the "cells" of turbulence that are flowing overhead. Much larger than this and the effective strehl of the optical system + atmosphere starts to drop off significantly.
What size is this? Well it depends on the steadiness of the seeing, so it'll change from night to night. Best case scenario (very steady seeing, and good location a-la a professional observatory) he estimates the cells are around 20cm across, so that gives an ideal aperture of 1.4m. Going much larger than this actually *decreases* the image quality as the image breaks up.
I wondered about the ideal aperture for the sort of seeing we get in Australia, most of the time it's much less than perfect. I'm going to enquire locally with some meteorologically connected friends and see if I can find out this "cell size", maybe it's something that's measured and recorded somewhere...?
If you knew the average size of these air cells for your local area then it would let you work out the largest mirror that would be all-round effective. Nothing stops you getting something larger, but you might find fewer nights where it goves a good result.
cheers, Bird
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