Re: ATM .75" secondary

["Dave Richardson" <yickityoptorus@hotmail.com>]

I've recently built one of the f10 scopes and it turned out exceptional in 
performance (For a little 3").  According to my calculations the ideal size 
for a diagonal is .6 inches.  I really wanted to avoid biting into this 
already small aperture (3") with an oversized secondary, so I searched hard 
for a small diagonal.  I found a .57 inch secondary which worked out very 
well.  It is unfortunately no longer available.  If you can find something a 
little smaller than .75, I would recommend doing so. I attribute my scope's 
good performance in part to the use of a small secondary which minimizes 
light blockage.  However, I am aware of how difficult it is to find them in 
these small sizes.

>From: ParkinStar@aol.com
>Reply-To: ParkinStar@aol.com
>To: atm@shore.net
>Subject: ATM .75" secondary
>Date: Mon, 7 Jan 2002 09:17:16 EST
>
>
>Does anyone know where I can find a couple of inexpensive .75" minor axis
>secondary mirrors? I am trying to put together two Surplus Shed scopes 
>using
>a 3" f/6 and a 3" f/10 primary. It appears that .75" is the right size for
>both focal lengths.
>
>Thank you in advance.
>Shaun Parkin
>Ashburn, VA
>




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