At 08:29 AM 9/29/98 +0800, Sean Chan wrote:
>Hi all,
>
>I'm wondering how useful the Varimagnifier is for fine focussing for
>Astro use?? There are 2 settings 1.7x and 2.5x I think. Would that be
>sufficient for focussing stars?? Apparently Vixen Telescope makers got
>a 6x magnifier but it's a separate item that can't lock onto the
>viewfinder...thus its has to be physically held next to the eyepiece
>making handling it and focussing it a little tedious.
>
>All opinions on this is greatly appreciated...thanks in advance,
>sean
>--
I find that the varimagnifider is an indespensible tool for focusing
through a telescope for a number of reasons. To begin with, it allows me
to comfortably view the image (it rotates 360º) when it would otherwise be
akward. When the tube is pointing near verticle, viewing through the
cameras viewfinder would require you to be on the ground looking up. With
the 90º rotating extension, I can position the viewer to a more comfortable
position.
More importantly, however, it allows me to do a precise focus with a
focusing mask, and the 2x magnification it provides. Simple put, when the
scope is pointed at a bright star (for focusing prior to framing the image)
the mask will produce a 'double' image of the star when the scope is out of
focus. Focusing is done by 'merging' the two stars together. The 2x
magnification lets me do this more precisely.
The varimagnifinder would also come in hand with other focusing methods
like the knife edge focusing technique. For further information about
focusing, try this page:
http://www.isomedia.com/homes/cvedeler/scope/focus.htm
I hope this helps you out.
Regards,
Dan Medley
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