ATM 11.2" F/2 Primary testing questions :)

["James Lerch" <jlerch1@tampabay.rr.com>]

Greetings all,

Construction has began on my 11.2" F/2 Dedicated CCD scope (CCD chip resides where secondary mirror would normally be)  I plan on stopping the primary down to F/2.5ish (most-likely) if coma becomes a problem.

While Trepanning and Hogging, I've been pondering the following questions, and would appreciate some input from the group.

#1  Just where do you measure the Roc on such a beast?  The difference in ROC between zone 1 and Zone 7 will be nearly 0.325" (8.25mm)  on a moving source tester.  With this fast of a primary, +/- 0.325" in ROC makes a fairly substantial difference on the Strehl Ratio.  I "Assume" the roc would be relative the Zone 1, but just wanted to make sure....

#2  With such a Fast Primary, I assume Foucault testing will be unsuccessful.  If so, would the Wire test be more appropriate?  Does anyone have a Web reference to the setup of a wire Tester?  If the Wire test is still inappropriate, I guess that would leave me with the Hartmann test or the Caustic test?  I've done a Harmann test with good results on more "Normal" mirrors, and I believe my current test platform will be sufficient for the caustic test,  I'm just looking for some guidance on which might be best/easiest ;)

I guess that's it for the moment, its time to go back to hogging while I look forward to your replies :)

Take Care,
James Lerch
http://Lerch.yi.org/atm (My Telescope  Construction Webpage)