P3D Re: S3D Re: Beam splitter options: please advise

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

In the future please post these kind of postings in photo-3d.

Thank you,-- George

Reply to message from SHIELDS@xxxxxxxxxxxxxxxxxx of Fri, 23 Jul
>
>What are usually called "beamsplitters" in stereo circles really
>aren't--there have been optical devices, particularly in movie
>cameras, that let part of the light go one way and part another
>way, whether a prism device or a partially-silvered mirror as in
>the Canon Pellix SLR. The common stereo beamsplitter divides the
>35mm format (24X36) into two halves, each 18X24. It usually uses mirrors, 
>although prism devices are out there.
>
>Any stereo photograph requires that the camera be held level,
>even if you are using a rail or slide bar for one camera and
>shifting it from side to side. Most beamsplitters, since they
>screw onto the front of a single lens, _do_ pose the additional
>requirement that they must be parallel to the camera body.
>An annoyance, to be sure, but one I'm willing to put up with.
>The Pentax is a good unit and very expensive new, but it is
>usually possible to find a good used one for less.
>
>Reading your other post, however, I don't think you will be
>happy with a common beamsplitter because it produces a vertical
>format. It's certainly not for everybody. I have a lot of half-frame
>experience and like the mild telephoto effect of a splitter on
>a 50mm lens. This is not the prevailing opinion--most stereo
>cameras produce an approximately square format using 35mm
>lenses. If 7 perf isn't wide enough for you, and the stuff
>at the edge is very important, you aren't going to be happy
>with 4 perf, which is what you'll get with a Pentax splitter.
>
>There was a really rare splitter on eBay recently--I think it's
>gone now--that produced over-and-under images on 35mm film--
>two images about 12X36--panoramic! I'm sorry but I don't 
>remember too much else about it. You could hunt around and
>ask questions if that's what you really want--research the closed
>auctions on eBay.
>
>Beamsplitters can produce excellent results if used correctly,
>but you must understand and accept their strengths and limitations,
>same as any other kind of equipment--will it really do what you
>expect it to do?
>
>Mark Shields
>
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