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Re: [ATM] 150 mm f/7 Refractor

Richard F.L.R. Snashall wrote:
> Schott's newest catalog release contains a new glass type N-KzFS8
> (720347.320).  Just about where Ohara S-NBH8 is.  About 6 times
> the cost of N-BK7.  Quite robust.  dPgf about a fifth of N-KzFS4 et.al.
Or you could just keep throwing chunks of BK7 at it:

Surf     Radius   Thickness      Glass   Diameter

 STO   Infinity   -6.383219                   150
   2      443.8        21.6      N-BK7        156
   3     -443.8         9.7    N-KZFS8        156
   4    -3512.9      411.38                   156
   5     492.77        14.1      N-BK7        114
   6    -464.47        91.4                   114
   7    -243.15         6.5      N-BK7         82
   8     463.14    400.8737                    82
 IMA   Infinity                                42

The minimum focus is just about at the e-line, which is also
highly corrected -- less than lambda/400 P-V on axis.  In
this case, the two smaller BK7 lenses also correct residual
coma, astigmatism and field curvature while compensating the
residual color of the doublet. The residual lateral color is
less than 0.1 micron C-F.  Some distortion is added -- under
7.5 microns at the field edge.

OT:

"He told you to stick the field flattener WHERE?";-)
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