Re: DOF/Dr. T/Merklinger Book

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

ted gosfield wrote:
> Would John B. or another DOF maven/wallah like to comment on the appropriate
> coc for stereo transparencies viewed in Red Dot or Kodaslide viewers?
> (surely we need not take this subject to tech-3d)

Well, let's see how many groans and scrams we get.  8-)

I feel more like a wallah than a maven.  The acceptable C of C depends on
the sort of resolution you need for the scene.  (Sounds like tautology.)
Some scenes have really sharp contrasty lines in them and for that you may 
want a sharp picture.  In that case, you may want to go for the gusto and 
get all the eye can see which is 1' of arc or 1 in 3400.  That's substantially
better than the usual 1 in 1000 or 1 in 1500.  Note that stereo photography 
again allows for very easy calculations because we view from the center of 
perspective.

One in 3400 is probably overdoing it 8-) if your film/lens will only support
40 lines per mm and you're in 5P using, say, a 35 mm lens.  40*35= 1400
so not going past one part in 1400 for your C of C would be reasonable.

One part in 1400 is 147" of arc so referring back to my earlier post,

D = 115/R = 115/147 = 0.8 mm
 
Lens focal length     f/number for 0.8 mm aperture
 
      35                         44
      50                         62
      80                        100
     150                        190

So you see you can stop down more to get to the diffraction limit if you
settle for 1 in 1400.

Don't forget to add all these sources of lack of resolution together in
quadrature (square root of the sum of the squares).

John B


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