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Subject: LX200: Forwarded Re: f/6.3 LX200s
From: Todd Gross
Reply To: mapug@shore.net
Date: Wed Jun 05 02:32:50 1996

>>> I hate to bug you, but can you elaborate on that one too.. It is a debate
>>> going on on MAPUG that I would like to solve

>No problem...
>The reducer noticeably degrades the images when you compare a native f/6.3 to an
>f/10 with reducer. Not only are stars not as crisp, but there is vignetting with
>wide-field oculars and a reducer that isn't present with the native f/6.3.
>Conversely, using that 8" f/6.3 at high power on planets revealed detail I never
>saw with any f/10 system - but I have to attribute that to unusually good optics
>on this one scope.

>It's also amazing that people will think a minor increase in
>secondary obstruction diameter would make any noticeable difference. The best
>SCT optics I've ever owned were an 8" f/6.3 (and I've had well over 20 SCTs).
>The wide fields of view were quite beautiful at that focal length.

>My 7" Mak has perfect optics, but the f/15 ratio is extremely limiting. When
>used with the f/6.3 reducer (which brings the 7" to f/9) the benefit of pinpoint
>stars is gone. When the 12" LX200 arrives I know the even more restricted field
>will be a concern, but at least it will do a better job on dim deep-sky objects.
>It would be nice to mount my 13" f/4.5 Coulter on an LXD750 mount for "go-to"
>capabilities. It has a perfect field size, light grasp, and very good optics.
>The big problem with the LXD GEMs is that it won't let you view a large area
>near the zenith (illegal position - will hit tripod leg). It was that reason I
>sold my 7" APO a few months ago.

-Todd
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Todd Gross, Ch. 7 Meteorologist, Boston
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