Re: [ATM] how good is this mirror?

[Richard <cnc@cncservo.co.uk>]

Hi Vikram,

Wednesday, October 5, 2005, 3:44:26 PM, you wrote:

VC> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7547170736&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1

1/4 wavlength surface accuracy will give 1/2 wavelength
wavefront accuracy. The normal recognised bare minimum to
satisfy Raliegh criterion is 1/4 wavelength wavefront error. it
is also very fast at f/3.69, so it will give poor performance
with bad coma. There also aren't many eyepieces, even expensive
ones, that will deeal with f/3.7. It also dioesn't say if that
error is RMS or P-V. If it's RMS then it's very poor indeed.
Google on "1/4 wavelength surface wavefront" without the quotes,
and the very first hit will give you some background info.

You could make one much better...

-- 

Best regards,
  Richard in the UK

_______________________________________________
ATM mailing list http://www.atmlist.net/