In article <4a6pbi@news-ipg.umds.ac.uk>, A.D.Smith@umds.ac.uk says...
>For some work we're involved in here, we need to take two photos of >operations taking place. At the moment we just use one camera and move >around, trying to get roughly in the same place after each pair of >shots. We can then correct for variations in positioning later by >computer re-processing. Is there any rig available to mount two cameras >about 1m apart, which we could use to take these shots more >reproducibly ? It would need to be easily moved
>around, and not too bulky as it would be used in an operating theatre.

It would seem to me that two cameras with built-in motor drives could
be easily mounted with standard 1/4" bolts (carefully!) using the
tripod sockets on the cameras and a bar of some easily cleaned material.
The cameras would need to be aimed in toward an average subject distance (1m spacing seems rather far apart - more suitable for clouds,
maybe, unless you want very exaggerated depth of the subject from a distance of many feet). AF might help if distance varies much in different photos. A TTL flash could be used, but should probably
be controlled by only one of the cameras, and could be mounted between
the two cameras (or, the controlling flash could be on one of the cameras, and a second flash [controlled by the first] could be mounted
near the second camera). If flash is used, both cameras need to fire
simultaneously (probably with a lower shutter speed set than the synch.
speed to make sure that both shutters are open during the flash - be
sure that you are using an aperture small enough to avoid ambient light
exposure if you use flash). Shutter release should probably be done
with a dual electronic cable release (you will need to make it from
two singles) rather than a dual mechanical release to assure that both cameras fire nearly simultaneously for the flash. (If you do not use
flash, many difficulties are removed [if there is enough ambient light - and it is my guess that there is].) A pistol-grip with a trigger could be mounted on the bar to help in handling the rig. (I have been meaning to build something like this for landscape/cloud photography ever since
I learned how easy it is to see 3D pairs directly without special optics
after seeing a book called "Stereograms" [Cadence Books] on the history
of 3D images, including the newest 3D computer images - great book!)
Hope this helps.