Quote:
Originally Posted by davidpretorius
Am i right in thinking, i should get a single diffraction ring in great seeing on a focussed star?
I seem to remember the Taks with diffraction rings, but i can't remember my newt ever having then?
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Dave this is why the pickering scale is referenced to a 5" refractor.
In the ed80 I had, diffraction rings were visible in anything but the most horrible seeing, whereas for my 10" newt it takes excellent seeing to see a diffraction ring. Its related to the aperture and the way light behaves.
You cant quote out of 10 seeing on the pickering scale in a meaningful way unless you have a 5" refractor, or have enough experience to know how the seeing would look in a 5" refractor on a given night.