Close-up lens depth of field

[P3D Jonathan Orovitz <jorovitz@xxxxxxxxx>]

Wed, 19 Feb 1997 Eric Drysdale <edrys@xxxxxxxxxxxxxxxxx> wrote:

>Hello all,
>O.K. I'm stumped.  I looked in the stereo realist manual and searched >the archive.  How do I determine my focus/depth of field when using >close-up lenses?

I'll bet John B. can produce the formula!

In the meantime, my old Vivitar Series V close up lenses came with a
chart.  I use the 50mm lens numbers knowing that I actually have a
little
more DOF with the Realist's 35mm lenses.  There is (or was) also a nice
cardboard calculator in Kodak's little Master Photo Guide.  I do not
know
whether it is in the current edition.

Although you may have a lot of close-up diopter power on your Realist
lenses, you soon have stereo base problems.  Without prisms or shifts, I
find that a standard Stereo Realist completely runs out of steam close
to 1.5 feet mark.  At that distance (46cm), your stereo base is still
7cm, giving a (min. distance:stereo base)ratio of about 6.5:1.  Your
usable picture area will be less than 4 perforations wide.  Various
rules of thumb suggest ratios between 30:1 and 50:1.  If your picture
contains no distant objects, you can use 15:1.  

For extreme static close-ups I favor a good SLR on a macro focusing bar. 
With a macro lens (and sometimes a bellows or teleconverter) I can get
within an inch of my subject at f/32. The SLR macro lens is far sharper
than the Realist's.  If your camera has depth of field preview, you can
eyeball the DOF.  A modern TTL flash, mounted off the camera, is very
handy for this kind of work.  For the finished product, I usually use 7P
(European style) stereo slide mounts.

Last year I shot some fruits and vegetables up close, 3-D, and personal.
I am really pleased with 3-D close-up of a single blackberry (made with
an SLR).

Jon Orovitz
"These opinions may not reflect the views of the management."


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