Quote:
Originally Posted by Wavytone
So far no-one with a scope faster than f/5 has fessed up concerning min/max magnifications ... Anyone ?
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I know someone in Perth who has changed from a quality 20" F5 to an F3.6 using it above 600X on good nights of seeing and has noticed absolutely no drop in resolution or contrast over the F5. That guy has retired his 12" Takahashi Mewlon as his reference planetary scope simply because it is being outgunned. Reports from another Melbourne ATMer that their F3.6 is holding its own against longer focal length in the same aperture.
I have not noticed any degradation in the quality of the Airy Pattern with such focal ratios under bench Null test, compared to an F5 they are just more time consuming to make. The current debate in the large mirror scene is over weather large mirrors should be left a little undercorrected. One US optician is making good money correcting the work of another who thinks they should, but whose mirrors just don't seem to be cutting it in the field. I personally believe that a mirror of any size should be fully corrected then thermally managed.
Nick- if you are at SPSP this year perhaps Paul Hatchman can show you through his 20" F3.6 ?