RE: [ATM] newt and 75% ray

["Alan Scott" <alanne1956@hotmail.com>]

Changing the size of the secondary will NOT help.  Your problem is that the 
1.25" focuser is blocking light.  Go to a 2" focuser.  Or, not.  I suspect 
that it will just limit the width of your field of view.  btw, 2" focusers 
are great.  Take a look at the Kine optics HC-2.  Cool focuser!

It looks like your secondary is plenty big.  I went with a 2.05" secondary, 
12" f5 mirror, and have great views of planets.  There are also no 
noticeable light drop off at the edge of the field with a 22mm 65 degree 
eyepiece.

I was surprised how easy it actually was to create a scope. (I did cheat and 
buy a primary finished.) Good luck, and have fun.

alan

http://www.xmission.com/~alanne/DS3Main.html


>From: "Dan Delzell" <dan@bogus.net>
>Reply-To: dan@delzell.net
>To: <atm@atmlist.net>
>Subject: [ATM] newt and 75% ray
>Date: Tue, 22 Mar 2005 18:13:12 -0600
>
>I keep designing telescope and never building one, but I think I have
>finally have a design I can build (I'm not the best wood worker).
>
>
>
>I've used newt to plot it, and it says that I have vignetting of the 75% 
>ray
>at the focuser with 1.25" eye pieces. It looks significant in the focuser
>view.
>
>
>
>Is this something I should worry about? And how can I change my design to
>fix this problem?
>
>
>
>The scope is a 14" f5 with a 2.6" secondary and low profile focuser.
>
>
>
>Thanks.
>
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