Re: ATM Mirror/Foucault readings

[Mel Bartels <mbartels@efn.org>]

Yes, your zonal figures for the 8" f/6.7 are correct:

>>> I get, for a 5 zone mask, based on Barrys instruction:
Zone 1: .007"
Zone 2: .022"
Zone 3: .037"
Zone 4: .052"
Zone 5: .067" <<<

Your actual readings of

>>> Zone 1:.016
Zone 2:.022
Zone 3:.016
Zone 4:.010
Zone 5:.019 <<<

...show approx sphere with high 80% zone.  Use 1/2 W with 1/2 wide
strokes MOT to speed this zone along, otherwise standard 1/3 W will
eventually go back to spherical.

Keep the lap in good contact during parabolization.  If the lap is
medium or hard, you should cold press every couple minutes.

-- 
Clear skies, Mel Bartels    Programmer/Analyst, amateur astronomer
Eugene, Oregon, USA         homepage: http://www.efn.org/~mbartels
mailto:mbartels@efn.org     atm, atm-digest list-owner
Motorize A Dob: http://zebu.uoregon.edu/~mbartels/altaz/altaz.html