Re: [photo-3d] Re: Newbie question-near point distance

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

>Hi George!

Hi Mike!

[long snip]

>So which do you prefer for dealing with a change in focal length?  
>David Lee's method or McKay's PePax rule (Wednesday or Friday)?

Me personally? Neither!

The only stereo camera I use that offers variable
focal length is an RBT X3 camera with 28-75mm zoom.
I move from 28 to 75mm without changing the stereo
base.  I also put 100 and 135mm lenses and I still
keep the same stereo base.

A few years back I was doing quite a bit of twin SLR
shooting.  Normally I would have both cameras side-by-
side on a bar, with 45mm lenses.  The physical size
of the cameras stopped me from getting them closer
together.  The only time I changed this was when I 
used 135mm lenses for close ups of animals, where I 
increased the camera separation.  The length of my
twin camera bar now dictated how far I could separate
them.

If the stereo base *needed* to be changed for every
change of focal length, then RBT would not be making
twin SLR stereo cameras with zoom lenses.  For twin 
cameras the practical limitations of how close or how 
far you can separate the two cameras usually dictate 
the choices.  

I do some amount of single camera work, either hand-held
or on a slide bar.  Slide bar pictures are all close
ups.  I don't measure anything in either case.  I
just shift as much as I think will give a good picture.
I have never had any real regrets regarding the stereo
base so I don't see why I should change what I am doing.

I understand that you are trying to point inconsistencies
in my postings, which should not be very difficult,
especially since my personal choices are based on 
photographic intuition and not calculations.  I am
sure you agree that there is room for both philosophies
in photography.  

Take care,

George

 

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