[ATM] f12 mirror advice requested

[Philip Lardner]

Yes - I recently finished a 14" f/15 (RofC=10,500mm) and found not just the
focal length but the figure to be extremely sensitive to change while
polishing. I ended up with a RofC = 10502mm and decided that was good
enough! Testing a mirror of that length wasn't easy either. The slightest
air currents really screwed things up, and it also showed up the surface
roughness in the video camera (and other lenses I used) as clear as day!

Phil.

-----Original Message-----
From: atm-bounces at atmlist.net [mailto:atm-bounces at atmlist.net]On Behalf Of
Gil McFarlane
Sent: 02 February 2007 18:49
To: ATM
Subject: [ATM] f12 mirror advice requested

I have been surprised at how easily the focal length
changes when smoothing this mirror - I am beginning to
suspect that there may other surprises in store as I
finish it up - any suggestions?  (it is a 5" diameter,
1" thick blank.)

- Gil