Quote:
Originally Posted by Greenswale
I use a 7mm XW Pentax in my F6 8" dob, with truly excellent results. I often use the wide field of view to let objects drift accross the field of view, so that I am more able to concentrate on the object itself, rather than on moving the scope. Depends on the object, though.
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Hi,
Using the drift method depends more on the scope, than the target. Your 8"/F6 scope has an infinitely larger diffraction limited field than the original posters 12"/F4.7 scope. The size of the diffraction limited field of a newtonian decreases logarithmically with a decrease in the F-Ratio of the scope.
This article by Bob Royce explains it all.
http://www.rfroyce.com/mirror_performance.htm
My experience at the eyepiece confirms exactly what Royce is saying in this article.
IME you can use the drift method very successfully with a 6"/F8 scope, with a fair degree of success with an 8"/F6 scope and with little success in any scope of F5 or faster, although a paracorr helps a lot with these faster scopes.
Cheers,
John B