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Re: ATM 100% illumination and secondary sizing

To: "David Moorhouse" <climber@world-net.co.nz>
Subject: Re: ATM 100% illumination and secondary sizing
From: "Vegos" <astro@rvi.net>
Date: Thu, 15 Mar 2001 18:13:54 -0800
Cc: <atm@shore.net>
References: <001e01c0adb8$b73a1a80$64121aac@tvnz.co.nz>
Reply-To: "Vegos" <astro@rvi.net>
Sender: owner-atm@shore.net


Hi David:

I'm working on the same configuration you are.  Received two 12.5" plate
glass blanks from Dan C. and intend to abuse them (as recently discussed)
into f/5.  Beautiful plate blanks from Dan BTW.

I'm going with the 2.6" secondary.  No particular reason other than any
contrast gain between 21% and 17% diameter will probably be below my
threshold to detect 99% of the time.  I'd rather have the secondary edge
less critical to good views with the bigger secondary than with the 2.14".
And if I ever do get any nice big wide field 2" low power eyepieces (ha) the
2.60" will give better illumination in that situation.

Steve
http://www.rvi.net/~yovw

References:
- ATM 100% illumination and secondary sizing
  - From: "David Moorhouse" <climber@world-net.co.nz>

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