Re: Ultra-quick evaluation of scanned photo with Mak lens

[aah@nofs.navy.mil]

Tom did a quick S/N analysis center-to-edge, which looks ok to me.  However,
a couple of points:
  (1) The flat field that Michael used was taken through the basic
        500mm f/5.6 lens.  If we wanted to make this lens into a
        350mm f/4 lens, the field cruncher will make the vignetting worse.
  (2) Since there is 0.5mag variation in actual signal center-to-edge, then
      you must be*very* careful in how you do your flatfielding so that any
      hint of that systematic trend is removed from the final data.
  (3) This also means any flatfield will have ~1/2 the signal in the edges, ok
      as long as the sampled dynamic range is linear.
  (4) My concern regarding scattered light remains, and will have to be
      tested with an actual system.
Still, unless Tom or someone else can come up with a better and/or cheaper
solution, one of these Mak systems sounds like the best initial choice
of aperture for the Mark IV.
Arne