Re: [ATM] Attempted Parametrization of a Petzval Design

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

Richard F.L.R. Snashall wrote:

>
>
>I selected the lens diameters, f/#, separation ratio,
>wavelengths and field.  After freezing the thicknesses and
>radii (manual intervention):
>
>Surf     Radius      Thickness      Glass      Diameter
>
>STO   Infinity      -6.652961                      290
>   2    1583.45             33       N-K5           300
>   3   -1583.45           5.55                      300
>   4   -1583.45           22.5         F2           300
>   5    49432.3         1909.1                      300
>   6    1017.51           22.4       N-K5           200
>   7   -1017.51              0                      200
>   8   -1017.51             15         F2           200
>   9    61956.2       1046.915                      200
>IMA  -3055.721                                42.27809
>
>The only bad ghost detected by ZEMAX is the reflection
>between the lenses of the second doublet;-)
>
However, both N-K5 and F2 have preferred block sizes of 190x180x140;
not all the 200 mm diameter is needed for that field, anyway; the
second lens could probably be cut down some:

Surf     Radius      Thickness      Glass      Diameter

 STO   Infinity      -6.653045                      290
   2    1583.43             33       N-K5           300
   3   -1583.43            5.5                      300
   4   -1583.43           22.5         F2           300
   5      49437         1909.7                      300
   6    1018.54           18.5       N-K5           175
   7   -1018.54              0                      175
   8   -1018.54           13.1         F2           175
   9    67621.7       1050.734                      175
 IMA  -3067.924                                42.27835

At 167 mm second doublet clear aperture, this still has about 4%
vignetting at the field edge.

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