Re: [ATM] Glass type

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

Lance, sorry for the late reply but at least it is here.
Sounds like you have a pair of glasses for a inexpensive
refractor.  You won't  get great performace out of that
combination but they will work together to make a nice guider
scope if you want.  On the other hand, you can also do something
of a fairly long focal length to reduce the color error that will
be ther to something usable.
Pick up GSUM and play with it a bit to reduce the LA error to a
minimum and build the refractor from those curves.  Do the
Fraunhofer version as that will have the least color.
As to the various glass types, the various glasses are all made
from different quqntities of various other materials included in
the silica to change the refraction of the glass.  BL-7 is the
common glass used a lot and it is close to plate glass in it's
composition and properties.  It isn't like Pyrex to any real
degree other than it is another glass.  I'll note that there are
thousands of different types of optical glass that have been made
over the years.  BSC-2 glass is very close to BL-6 and is often
used instead of it in lower quality lenses.  I've got the indices
of that glass in some of the catalogs on my website.  BL-7 is
5176442 while BSC-2 is 517645 for the standard designation of the
glass.  The standard designator for glass is composed of the
first three digits of the Nd value and the first three digits of
the Vd of the glass.
Bob May
bobmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
Replace the obvious words with the proper character.

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