Re: Looking for advice on finderscopes.

Tony Flanders wrote:
> The main reason that I prefer a unit-power finder for
> this purpose is that it has infinite eye relief. A
> finderscope requires you to stick your eye right
> against it, which is invariably awkward and/or
> painful with a straight-through unit when pointed
> near the zenith. That's doubly true for me, since
> I favor low telescopes and a seated observing
> position.

It's only necessary to put your eye up against it when you're using
it as an optical finder. If you use it like a Telrad, you only need
the very center of the field of view and can pull your eyeball back
away from it to a comfortable distance. (Well, comfortable to me,
anyway, except near the poles.)

The same tactic is used by quite a folks when using short focal length
orthos or Plossls on planets in a driven scope. Since the motor drive
keeps the target centered, the size of the field of view is less
important (it still makes it easier to find the target, of course) and
you can use only the central 20 degrees of the AFOV, say, and observe
in relative comfort.

Pursuant to another thread, pulling back from the eyepiece to improve
comfort at the expense of AFOV is one thing I'd consider to be a useful
astronomy hack.

--
Brian Tung <brian@xxxxxxx>
The Astronomy Corner at http://astro.isi.edu/
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My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt
.

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