Double depth

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

There are various rules for the maximum allowable depth in a 
scene.  Seems like the best ones have to do with the maximum 
amount of parallax on the film and that that amount is usually 
about 1/30 of the focal length of the system.  

For miniature format with the usual 35 mm lenses, this works 
out to about 1.2 mm of parallax.  If a scene has a lot of depth 
in it, some people will crop the mask a similar amount for 
"double depth".  Does this cause viewing problems?  I think I 
can see where it would be a problem for projection because the 
window would be really close, but what about in a hand viewer?

The reason I ask is that I just calculated the way I set the 
window in my medium format viewer and it's at about 4' (1.2 m) 
which is approximately double depth.  I have no problem with it.  
I haven't heard of anyone having a problem with it.

So if double depth isn't a problem, where does this limit to 
the amount of a depth in a scene come from?

Thanks,
John B


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End of TECH3D Digest 32
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