[photo-3d] DOF & Rangefinder

["Chuck" <cfholzner@xxxxxxxx>]

I really don't know what is meant by "I don't use a rangefinder, I use
maximum DOF."  All I can assume is that they use their tightest F stop and
focus for about 15 feet.  The problems with this are the tightest F stop
rarely produces the sharpest photos and many stereo cameras vignette badly
at F22.

I use a rangefinder AND DOF.  With the rangefinder, I measure the distance
to the nearest object I want in focus.  I then measure the distance to the
farthest object, then set the camera focus between the near and far distance
with the two distances at similar F stop markings on the DOF scale. This
gives the same sharpness at near and far with everything in between sharper.
I then select the F stop based on light, lens sharpness, and DOF.  Mostly I
use F11 or F16.

It is easier if I have infinity or very far objects in the picture.  I use
the rangefinder to measure the distance to the nearest object and then set
the focus to twice that range.  This is the principal behind the hyperfocal
table in the older Realists.

In any case, if you are going to adjust the focus, you should know the
distance to the objects you are photographing and the handiest way is with a
rangefinder.


Chuck Holzner