Re: [ATM] 4.5"x 3/4" Pyrex disks at Surplus Shed and Acculap

[Jonathan Lavoie <atm@lavoielactee.net>]

----- Original Message ----- 
From: "Bob May" <bobmay@nethere.com>
To: <atm@atmlist.net>
Sent: Saturday, June 11, 2005 7:50 PM
Subject: Re: [ATM] 4.5"x 3/4" Pyrex disks at Surplus Shed and Acculap


> If I bought one of those mirror blanks, I'd do a nice long planetary scope
> with it.
> You can easily do a F16 (70"FL) or so and get some great views of the
> planets with it.  The nice thing is that the parabola is hardly needed to
be
> found for such a scope as a sphere will do pretty well and be well within
> the 1/4 wave criteria for an average scope.

And even better if you make it an ellipse by moving the source towards the
mirror and the knife edge as far as possible, then it is the same figuring
work as a sphere...

Jonathan

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