Re: [photo-3d] Re: Re: DOF & Rangefinder

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

Greg wrote:

>WHEN THE RANGEFINDER IS INDISPENSABLE - When you are interested in and
>specific object, focus on it using the rangefinder (especially is adjusted
>by the tanker) and shoot at the smallest f-stop and slowest shutter
>combination you determine you can live with.

The rangefinder might appear to be accurate but does
it coincide with the true focusing of the camera?
First the focusing of the camera must be checked and
adjusted if necessary.  With the focusing adjusted then
the rangefinder can be adjusted.

Both adjustments are usually done at infinity.  But do
they still hold true at a close-up?

It is getting a bit tricky as you can see.  Nevertheless,
small deviations are unimportant.  If the rangefinder is
a little bit off or the focusing is a little bit off,
it would make no difference in the final results.

Greg's advice to use the smallest f-stop and the
slower shutter speed combination reminded me when
I was in my first rolls of film.  I was using
something like f16 or f22 and 1/25 shutter speed.
Pictures turned out slightly blurred.  I thought
I needed more DOF and continued on the wrong path.
The problem of course was that at 1/25 second hand-held
you must have a very steady hand or support to get
sharp pictures.

When was in my 2nd year of stereo photography I went
through a period of disappointment when pictures of
my young daughter were out of focus because she was
moving during the exposure.  Everything was sharp 
except for the most important part of the picture, 
my subject (daughter).  That's a problem when 
photographing children who never stay still.

So you have to think hard about the slowest shutter 
speed you determine you can live with.  I advise 
people to give priority to faster shutter speeds 
over smaller apertures.  There is a lot of depth
of field at f8.  You don't need f16 in most 
situations.  But you do need faster shutter speeds
when you hand-hold the stereo camera.

George Themelis