[photo-3d] Beam splitters vs. Image splitters

[Bryan Mumford <bryan@xxxxxxxxxxxx>]

I admit to being new to the field, and I am willing to try to use 
correct terminology, but in my observations so far I have found that 
colloquial usage of "beamsplitter" means a device with mirrors to 
create a stereo pair in a single frame. Internet searches support 
this usage. Whether or not it is technically correct, if you want to 
research the subject, you had better accept that the devices are 
commonly called by this name. Maybe it's like the millennium. You may 
have been correct to celebrate this year, but everyone else 
celebrated last year!

If you are willing to educate me further, I'm curious why beam 
splitters are used in photography. Why do you wish to capture the 
same scene on two cameras?




>What are you guys talking about?   To my knowledge, Pentax never made a
>beamsplitter.  They did make some image splitters that split the image into
>two, narrow side-by-side images.  But a beamsplitter doesn't do that.  As I
>have explained many times, a beamsplitter requires two cameras at 90 degrees
>from each other and 45 degrees incident to the surface for stereoscopic
>photography.
>
>A beamsplitter permits full size (full width and full height) images.  Good
>quality beamsplitters are AR coated, and transmit about 48% of the light and
>reflect about the same (depending upon the efficiency, around 4% of the
>light is lost in absorption).


Bryan Mumford
Santa Barbara, California
http://www.bmumford.com