Re: [photo-3d] Depthmaster Auotfocus

[Paul Talbot <list_post@xxxxxxxxx>]

Allan Griffin wrote:

> George,  while I wouldn't say too much about the Stereo Graphic, I can say
> that, in the case where one uses a pair of long lenses in a twin-SLR-rig
> set-up and you are wanting to stretch the depth-of-field (dof) a little, it
> DOES help if you set one lens a little in front of your chosen dof setting
> and the other a little behind same.  While it is probably question of
> degree, one would need to experiment.  However, in my case, I guess I
> haven't pushed my luck too far but I can say that there is validity to the
> theory.  For some reason, the brain appears to "read" the sharper version to
> a higher degree than the other.

A similar effect occurs with slight mismatches of exposure: you
can attain a slight increase in the dynamic range of the film by
exposing the left and right images a little bit differently.  The
brain is able to pick up the increased shadow detail of one image
as well as the increased highlight detail of the other and merge
them successfully.  But there is definitely a limit to how much
difference will be tolerated, and the limit may vary from scene
to scene.  Many people will automatically criticize the view as
flawed due to the exposure difference, especially with a stereocard
where the two images are seen separately before and/or after viewing
in 3D.  I wouldn't recommend this as an approach that should be used
all the time, but it may help in some circumstances.

Paul Talbot