Re: [ATM] Finder

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Richard F.L.R. Snashall wrote:
> I spent some time scrounging through some surplus lens sites.
> I did not yet find a match that worked for a larger size.  I
> did, however, find [SS == Surplus Shed]:
>
> Title: Ptz08-14kx
> 48 mm f/6.367 Refractor Using Surplus Lenses
> VS: 0.8157 at +0.0084 mm shift
> VS: 0.4403 at 3.93 degrees
> Min: 535.022 nm
> Sugg: SS L7021 (50 mm 125 mm f.l. isoconvex)
> Sugg: SS L4521 (47.6 mm 154 mm f.l. planoconvex)
> Sugg: SS L8032 (43 mm -71 mm f.l. isoconcave)
Surplus shed was not able to confirm that these lenses were
actually made of BK7.  I suppose it would actually take
a measurement to be more sure.

However, I found this site:

     Rolyn Optics Company <http://www.rolyn.com/index.htm>

They have some 50 mm diameter B270 lenses, while not
as inexpensive as the surplus lenses, that are not as
high priced as normal lenses.  It also did not appear
to me that their sales were restricted.

The last doublet in these designs does not have as high
a dependence on refractive index.  Maybe one can get away
with using B270 in it.

Keeping the same first Surplus Shed lens (48 mm f/6.34):

    http://users.rcn.com/rflrs/Ptz09-70x.atm   ATMOS input file
    http://users.rcn.com/rflrs/Ptz09-70x.len   OSLO input file
    http://users.rcn.com/rflrs/Ptz09-70x.txt   TEXT prescription
    http://users.rcn.com/rflrs/Ptz09-70x.zmx   ZEMAX input file

If it turns out that the Surplus Shed lens is not BK7 or N-BK7,
the first doublet here is still a simple air-spaced Littrow
in common glasses.  The Visual Strehl runs from 0.8290 to 0.6053
over the eight degree field.  The field is quite flat -- within
about 7 microns.

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