Re: To Box or Not?

[koganlee@xxxxxxxxxxxxx]

On 10/29/98 08:11:34 you wrote:
>
>Opinions?
>Considering that almost all stereo photographs are taken at
>f16-f32, is there any reasonable arguments against not making a
>fixed hyperfocus box stereo camera? If the focus is set at, say,
>30ft, most depth of field ranges would span from 8-10ft to
>infinity at f16+. This would greatly simplify camera
>construction. Any significant drawbacks?
>
>Paul A. Lehman
>
>

This is an interesting question to which I have given much thought. What it 
boils down to is what percentage of potential exposures you would be able to 
make with it (as opposed to a focusable camera) versus how much more trouble 
it would be for you to make it.

I too faced this question. I eventually intend to make a focusable version, 
but knew it would be a while before I would have the time to do it, so I 
made a non-focusable one first so I would at least have something. Even that 
took quite a bit of work.

I am using two 120mm view camera lenses and made two 4x5 boxes for them. 
This is because it is important to me to be able to vary the distance 
between the lenses and I can get them 5.5 inches apart at the closest. I 
calculated the depth of field to extend from 9 feet to infinity at f45. I 
can get down to about 7 feet at f64. While I can see a very slight lessening 
in sharpness (under magnification) at the extremes of distance, everything 
is acceptably sharp to me under normal viewing conditions. This is, of 
course, something you would have to decide for yourself. It seems to work 
well. The first image I made with it has won Best of Show in 2 stereo card 
competitions. (Fallen Aspen for those in APEC.)

If you decide to use this method I would suggest that you carefully focus 
the lenses (one at a time of course) on a view camera, placing markers at 
various distances in the scene. Make exposures on transparency film and 
carefully examine the film with a magnifying glass to see 1)whether the 
lense is focussing where you are intending it to focus (you probably want to 
do this at a large aperture), and 2)whether it gives you the depth of field 
you want at the proposed shooting aperture. This may take several trials to 
determine. When you have got it just the way you want it, measure the 
distance from the front of the lensboard to the surface of the film, 
and reproduce this distance in you new camera. If you're using 4x5 and want 
tips on how to make the back of the camera, let me know. By the way, I 
highly recommend the Kodak Readyload 4x5 holders. They are light, 
convenient, and avoid the problem of dust particles on the film.

David Lee