RE: [APML] IC 410 uploaded and IC 405 adjusted

["Greg Hartke" <ghartke@adelphia.net>]

Hi, Alan,

Without actually seeing your equipment, it's difficult to say. Let's assume
that the adaptor inner diameter is narrower than the focus drawtube. If
that's the case, then moving the step that exists between the drawtube and
the adaptor closer to the focus plane would indeed reduce the potential for
vignetting. Did you get the private E-mail I sent you from work today? I
mentioned a technique whereby you can easily determine if you have
vignetting in your imaging system. Try this with and without the extra
adaptor and see what you find. I would certainly be worried that a reducer
in front of the TT III could cause vignetting so it would be a good idea to
do this test. If you want to use a reducer you'd likely be better served
using (gulp!) a guidescope.

Regards,

Greg

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Alan Voetsch
Sent: Tuesday, November 02, 2004 6:41 PM
To: Discussion of Film Astrophotography
Subject: RE: [APML] IC 410 uploaded and IC 405 adjusted

Hey Greg,

--- Greg Hartke <ghartke@adelphia.net> wrote:
> be happening with vignetting. It's also worth mentioning that in
> essence the
> T-stop might be considered to vary across the focal plane if there's
> vignetting. Yuck!

That's one more thing I don't need. I've got enough problems. 8-) I was
looking at the Taurus adapter between the "Feldstein Adapter' and the
Taurus body. It's one that's made to hold a reducer so it's longer than
normal. Do you think replacing it with a shorter adapter would help
bring the camera focus in a bit?

Alan

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