From: "Bob May" 
To: "atmlist" 
Reply-To: "Bob May" 


If you really want to have fun, make up some finder scopes just for the fun
of it.  I've got a program on my site called GSUM which is an old shortcut
to designing doublets for astro use that a guy named Guy developed during
WW2.  He never went on to do a form of the calculations for the triplet but
the doublet design will do very nicely for an acromatic doublet and its
numbers are very close to what a good raytracing program does today. Since
you have three different glasses available, you can use different
combinations for different powers and probably get away with it very
nicely. After that, there are several designs for eyepieces that can be
done quite nicely by the use of acromatic doublets (the Plossl design is
two doublets with the crown element pointed towards each other. FWIW, the
lower refractive indexes are crown glasses while the higher ones are called
flints.
To run GSUM, you need to know the refractive index at the C line, the
dispersion and the V value for each of the glasses. Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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