Re: [photo-3d] RE: Depth ranges

[Paul Talbot <list_post@xxxxxxxxx>]

"David W. Kesner" wrote:

> With the RBT I can't [limit the near point]. Remember, to focus
> I have to move the whole unit toward or away from the subject

Sorry, I didn't understand that.  In that case, you cannot
include "infinity" in your scene.  So the original mystery
as to why your ladybug image has too much deviation while
the mushroom image does not boils down to this: the maker of
the mushroom image used equipment that allowed him to choose
a stereo base appropriate for his combination of near point
and far point, whereas the limitations of your equipment did
not give you that flexibility.  (But the SLR on-a-slide bar
probably could not have recorded your ladybug image.)

BTW, it sounds like you are saying you move the camera so
that the near object is in critical focus.  Don't you have
some flexibility to move the camera forward or back of that
point and let the depth of field make the subject acceptably
sharp instead of dead-on in focus?

> Basically what I am asking is how far away can my far point be
> with a given magnification (1:1, 1:2, 1:3, etc.).

I don't fully understand how the magnification works on your
camera, so I don't know how to factor that into the equation.
But to calculate an answer, you need to know with certainty
the near point distance.  So far you have only stated a general
number (less than 12 inches).

Paul Talbot

 

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