[MF3D.FORUM:548] Re: Exact fl match for paired lenses.

[Paul Talbot <ptww@xxxxxxxxx>]

Bill Glickman wrote:

> Some of the responses leads me to a question, I am confused what the proper
> answer is.  If one shoots with subjects from 8 ft to 20 ft, and instead of a
> stereo base of 65mm, I use my min. base of say 125mm, 2x larger than John
> B's formula suggest.  IF the shot was taken proper, no toe in, cameras
> parallel, no camera tilt, etc..... Is the consensus that these shots, if
> mounted properly will view  perfectly fine  - as if the base was 65mm, the
> only difference being a bit more feeling of depth?

No, that is not the consensus.  If you use a base that is twice
what the formula says will produce MAOFD (maximum allowable
on-film
deviation) then your shot will have MUCH MORE than the maximum
OFD--
meaning most people will not be able to fuse the images
correctly.

To mount the images for satisfactory viewing, you have to:
  a) push the chips closer together so the far point separation
     is within proper limits;
  b) crop the image from the sides to eliminate the excess
non-stereo
     information and set a proper window.

If you have done a) without doing b), most or all of the scene
would be in front of the window, probably causing massive window
violation problems, including double edges.

b) is why there are "close up" mounts for 35mm stereo.  We don't
have close up mounts in MF, but a 645 portrait mount can be use
to provide the cropping needed.  You give up a lot of image area,
however.

If you use the distance to the NEAREST object (like the grass you
mentioned) in the formula, did you shoot with too large of a
base?

Paul Talbot