Differential macro focus

[P3D <gosfield@xxxxxxxxxxxxxxxxx>]

hi

Check Alfred A. Blaker "Scientific Photography" and "Field Photography" 
for a discussion of stereo macro photography.  He shows examples of 
stereo macro pairs with differential focus which work quite well.  You 
have to apply the technique with some self restraint.  

For a discussion of depth of field in Macro, with techniques and 
nomographs to be used in figuring out the acceptable subject dimensions 
and shape at different magnifications on film, check Kodak's (out of 
print) pamphlet on close up and macro photography.  I think the title is 
"Close up and Macro Photography" but i don't have it to hand right now.

I agree with George that it would not work for near-far images.  But if
the differential focus is reasonably close to the depth of field through
one lens, then it seems to work.  This is an old microscopist's trick to
combine images taken at the limits of the depth of field of the microscope
view.  If applied over too large a focus difference, there would, of
course, be a change in the differential perceived magnification between
the two images, with attendant stereo disaster.

good luck

ted gosfield
gosfield@xxxxxxxxxxxxxxxxx



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