Re: [photo-3d] Re: Are beamsplitters crappy?

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

----- Original Message -----
From: "Mark Shields" <beamsplitter@xxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Tuesday, January 09, 2001 2:30 PM
Subject: [photo-3d] Re: Are beamsplitters crappy?

The common use of the word beamsplitter is not the Pentax-style device,
which is an image splitter.  To understand the use of two cameras with a
beamsplitter, see my other postings.

JR

> I always enjoy it when beamsplitters come up again--don't get
> too much chance to discuss them!
>
> A pro and a con:
>
> I forgot to mention the glorious ease of mounting of beamsplitter
> shots (and I do mean the Pentax-style, common-use-of-the-term
> item)--you can let anybody at all do it, or you can easily do
> it yourself. I do it myself for two reasons. First, they tend
> to come back a little off center sometimes. Since they are so
> easy to mount, I don't mind doing it myself. Second, since I also
> send Nimslo slide rolls to the same lab, I don't want them to
> get confused. I hope by now they are used to the fact that when
> they see something coming from me, they will automatically think
> "Do Not Mount--Do Not Cut."
>
> On the other hand, while you can easily take reasonably fast action
> shots with a beamsplitter on any SLR, those with a horizontally
> running shutter, like my Olympus OM-10, will give you a problem
> with faster action, no matter what speed you use. That's because
> the speed is achieved by passing a variably narrow slit past the
> film at the same rate of speed, about 1/60 to 1/125 second. This
> does cause a problem for me sometimes. I get two different images
> of the action. If your SLR has a vertically running shutter, no problem.
> This same phenomenon will also cause linear distortion of
> a flattie image if the camera moves up or down significantly
> during the exposure, and the subject is moving fast. I've seen
> some very interesting train shots where this happened!
>
> As to the comment about the reason for using two cameras, I'm not
> sure I understand the question, but I would say it's for taking
> stereo pictures, one image from each camera!  :-)
>
> Mark
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>
>
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