Re: [APML] focusing question for reflectors

["Mike & Dianna" <galaxy@ncweb.com>]

Hi Mark,

You probobly would want to look into a combination of using a lower profile
focuser and moving the primary. I wouldnt trust those tall rack-n-pinions
that come stock on some of those scopes for keeping focus once your there.
Look into an aftermarket 2" crayford or helical. I like the helical myself
and use a Ceravolo helical on my 8" F3.5 newt.
I ,like Bobby, have 3 sets of holes in my ota for movement of the primary if
needed. If you want to do any prime focus work with your scope, moving the
primary is more than likely an option that you'll have to do.

BTW: How are you focusing ? From my experiances with an OM-1 and an OM-10,
just looking through the view finder even with a bright screen will not give
you accurate prime focus. After knife edge focusing my newts then looking
through the viewfinder, the stars are slightly blurry.

My advice is get a good knife edge and a good low profile focuser. With the
knife edge and focuser in place , then you can determine if the primary
needs moved forward as your last step.
 On another note, my guess on that Orion 6", that the secondary is probobly
to small to fully illuminate the 35mm frame, Im not sure what size is in
yours. You might want to look into that down the road.

Sincerely,
Mike Leitch
galaxy@ncweb.com
Astrophotography website
http://www.ncweb.com/~galaxy/home/astropho.htm
----- Original Message -----
From: m.dyer <mr.m.dyer@worldnet.att.net>
To: Astro-Photo (E-mail) <astro-photo@seds.org>
Sent: Saturday, January 05, 2002 12:19 PM
Subject: [APML] focusing question for reflectors


> Hello all:)
>
> I have been trying my hand at astrophotography with an Orion SVD 6"  and
> Olympus OM 1/10 cameras.  When trying to focus using the Prime focusing
> method, it seems that I can not get the  camera far enough forward - into
> the telescope.  It comes up just short of sharp:(  I was told that I may
> have to drill new holes in the tube and move the primary mirror forward,
but
> that idea doesn't appeal to me.  Are there any other options - a low
profile
> focusing assembly, or special t-ring adapter?
>
> Thanks in advance:)
>
> Mark Dyer
>
>
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