Re: Franks Bean Splitter

[Peter Davis <pdavis@xxxxxxxxxxxxxxxxxx>]

> 
> New to the technique and was wondering if the Franka Beam Splitter was a 
> good way to get my feet wet in 3D?  Any comments in general on Beam 
> Splitters?
> 

Just to give you my bias, I took my first stereo pictures with the
Franka splitter.  I sold it after I bought a Realist stereo camera.
However, I'm now thinking about getting another, higher quality
splitter.

That said, I think the splitter is a good way to get started, and even
go beyond that in stereo photography.  It has two main drawbacks:

   1)   It splits a regular 35mm image area vertically, so you get
        tall, thin pictures.

   2)   It introduces an element of "keystone" distortion, due to the
        fact that path from front-of-lens to film plane is different
        in different parts of the image.  My experience, however, was
        that this was not noticable unless you're taking a picture of
        a brick wall or some other grid.

   3)   It may make your camera somewhat bulky.

On the plus side, the splitter has these advantages:

   1)   You can use it on a modern, high-tech camera with whatever
        up-to-date features you desire.

   2)   No special processing or mounting is required.  The images
        are always perfectly registered, etc.

   3)   The images are always perfectly synchronized, and get the
        identical exposure settings.

   4)   You can take it off and shoot "mono" pictures on the
        same roll of film.

The Franka splitter I had was a lightweight plastic thing with rear
surface mirrors, which means you get additional distortion, blurring,
etc. because the light has to travel through the glass of the mirrors
twice.  For about the same price, you can get a somewhat fancier
imported splitter with better mirrors, etc. from Joel Alpers and, I
believe, some others on this list.  Their splitter can also be used as
a viewer for split slides.

-pd
--------
Peter Davis                    "Education is not the             617/873-4145
BBN Educational Technologies    filling of a pail, but      FAX: 617/873-2455
70 Fawcett Street               the lighting of a fire."       pdavis@xxxxxxx
Cambridge, MA 02138                     -- W. B. Yeats

        URL:  http://copernicus.bbn.com/people/PDavis/


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