[ATM] Finder

[Richard F.L.R. Snashall]

Richard F.L.R. Snashall wrote:
>
>
> Even then, the last doublet no longer has matching OTS
> surfaces.
With a more vignetting (40% throughput at the field
edge) and less magnification (7 mm exit pupil),
however:

Title: Ptz07-17x
48.8 mm f/6 Refractor with Erfle Eyepiece
Field: 8.2 Degrees
AFOV: 62+ Degrees
Sugg: MG LDX189 and LPX259
Sugg: MG LDX145(2) (and LPX249 in a pinch)

Surf     Radius   Thickness     Glass   Diameter

 STO   Infinity   -2.303521                 48.8
   2     130.38           8     N-BK7       50.8
   3    -130.38       0.341                 50.8
   4    -130.38           3      N-F2       50.8
   5   Infinity     184.085                 50.8
   6     91.814         6.6     N-BK7       50.8
   7   Infinity      30.266                 50.8
   8    -91.814           3    N-BAK2       39.2
   9     130.38    54.97938                 39.2
  10   Infinity    21.38537             42.23387
  11     77.038        11.5     N-BK7       50.8
  12    -77.038           3     N-SF1       50.8
  13     77.038        11.5     N-BK7       50.8
  14    -77.038         0.1                 50.8
  15   Infinity       7.316     N-BK7       50.8
  16    -77.038         0.1                 50.8
  17     77.038        11.5   N-LAF34       50.8
  18    -77.038           3     N-SF5       50.8
  19   Infinity    33.42887                 50.8
 IMA   Infinity                          9.19121

That middle lens in the eyepiece is designed so the
spacers have the same length as if the MG lens were
used.  Even then, the external spacing (21.38537 and
33.42887) will change with the substitution.