Re: ATM 90mm f-11 APO

["Bob May" <bobmay@nethere.com>]

Unfortunately, refractor designs have a big variable in the actual glasses
used - even to the point where different melts of the glass type change the
ROCs of the various surfaces.  You need to actually calculate out the curves
you need AFTER you get the glasses.  Another reason why high performance
optics is so expensive.  Additionally, you will be paying absolutely silly
prices for the glass itself!  FWIW, I have a pair of glasses for a 6"
refractor that I am happy to have paid only $600 for them - a price way
below the price that was originally paid for them 20 years ago.
Are you sure you really want to do a refractor?
Bob May
http://nav.to/bobmay
bobmay@nethere.com