P3D DOF and Hyperfocal distance - part IV

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Thank you for the warm reception of my previous messages in this
subject! :-)  Yes, most of what I wrote applies for 35mm film and
35mm lenses, like the ones found in most stereo cameras from the
'50s.

Two more fine points:

When I got started in stereo with a Realist, I made the mistake
to favor small apertures over faster shutter speeds.  For example,
I was shooting at f16 and 1/50 instead of f11 and 1/100. Some of
my first pictures turned a bit soft.  I thought I needed an even 
smaller aperture so I used f22 and 1/25.  The pictures turned out
fuzzier!  Of course, now I know that this was a mistake.  Without
a strong foreground, THERE IS PLENTY OF DEPTH OF FIELD AT F8!!!

If you hand held the camera and you have a choice, you should favor 
faster shutter speeds over smaller apertures.  Using too wide of
an aperture will lead to out-of-focus areas, but around the focusing
plane things will be sharp.  While if you shake the camera then
everything will be out of focus!

The second fine point is regarding the use of hyperfocal focusing. 
Take a look at the work of Harold M. Merklinger (thanks to John
Goodman who posted this reference): http://fox.nstn.ca/~hmmerk/
Harold has argued that nearby objects need less resolution to be
resolved than far away objects which are small and have fine
details.  He advocates focusing right at infinity in many cases.
For those who have worked with DOF concepts, focusing at infinity
sounds like a waste of good depth of field.  Everything past
infinity is wasted.  Yes, that's true.  But infinity is as sharp
as it gets.  If you do not have objects close to the camera and
you are photographing a scene is a nice weather and with good
details far away, consider focusing right at infinity.

George Themelis


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