[ATM] My conversation with Al Nagler - an experimental ParaCorr for f/3?

[Richard F.L.R. Snashall]

Richard F.L.R. Snashall wrote:
>
> It can probably all fit in a 2" OD barrel, and still
> have better than 70% illumination at the edge of a
> one degree field of view.
>
Of course, if you wanted to increase the aperture and
still keep the +/-0.5 degree field, the tube diameter
has to increase to keep the vignetting down.  If, say,
you wanted a 625 mm primary and wanted to use a 2.7"
ID tube, you might get something like:

Title: subapcorr01-32x
625 mm f/3 Newtonian with Coma Corrector

Surf     Radius   Thickness    Glass   Diameter   Conic

 STO   Infinity    13.02083                 625       0
   2      -3750   -1692.981   MIRROR        625      -1
   3      -71.6        -4.9    N-BK7         64       0
   4      -93.3       -46.4                  64       0
   5       -152          -2    N-BK7         50       0
   6      -56.5      -104.3                  50       0
   7    -103.74          -6    N-BK7         50       0
   8   Infinity      -34.34                  50       0
 IMA   Infinity                              37       0

of course, taking the temptation to use an OTS lens for
a close match, even if it does lose a little...
interesting new part number LPX-50.0-103.7-C.