P3D OLYMPUS XA and XA2 STEREO TWIN RIGS

["Ray Moxom" <raymoxom@xxxxxxxxxxx>]

OLYMPUS XA and XA2 STEREO TWIN RIGS
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In PHOTO-3D Digest 3121 Gary Schacker  < fotoschack@xxxxxxxxx> wrote:

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P3D Credit Where It's Due Message-ID: 
<13741-3679A241-822@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>

Many of you may know Joel Alpers of "Rocky Mountain Memories". 

One of the many fine products and services he offers is the twinned 
OlympusXA-2 rig. Now there's two ways in which you can get one of these. 
You can buy it ready made from Joel, or you can supply the cameras and 
he'll twin them for you. Both at very reasonable prices. I chose to go 
the latter route. When using auto exposure cameras for stereo, there is 
always the possibility that the exposures chosen by the cameras will not 
match. 

Being aware of this, I was careful to at least listen to my two examples 
to be reasonably confident that they were choosing similar shutter 
speeds under various lighting conditions. I sent them off to Joel who 
did a very neat job on them and also supplied a high quality custom bar 
for them to sit on. Much to my chagrin, the first two test rolls were at 
least two stops different from each other!  The cameras were indeed 
choosing similar speeds, it was the apertures that were different! Joel 
assured me that this was a rarity. 

Usually if they sound the same they are the same, or close to it. So why 
am a telling you all this? Because even though this was really my screw 
up, Joel was kind enough to take them back, open them up, adjust and 
test them until they were a good match. I'm sure it took plenty of time. 
He even sent back test shots so I could see how close the exposures are. 
All at no extra charge. When you do business with Joel, Dr. T, and 
others on this list you often get more than you expect (or deserve). 
Gary Schacker
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MY COMMENTS ON THIS ARE AS FOLLOWS:
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When using slide film, there would seem to be a fundamental problem in 
coupling two cameras and allowing each camera to use its own automatic 
exposure control particularly if the slides are to be used for 
projection. A one half stop exposure difference between left and right 
images can be very disturbing to the audience.  

With two automatic cameras displaced by at least 100 mm (4 inches) there 
is a good chance that even a perfectly matched pair of cameras will give 
slightly different readings.  For example, a shadow can fall on one lens 
and not the other or there can be a brighter area within the exposure 
meterís field of one camera when compared with the other.

In my opinion, a far better approach is to use a pair of Olympus XAs, 
rather than XA2s and have them connected such that one camera becomes 
the master and the other the slave. That is use the exposure control on 
one camera to control both cameras.  This is the approach that has been 
taken with considerable success by stereo workers in The Netherlands, 
Switzerland and Australia.  It requires a 4 wire connection between the 
two cameras to parallel the two shutter solenoids.  The battery is 
removed from the slave camera.  One battery is sufficient to fire both 
sets of shutters.

When Nancy (wife) and I went to the ISU Congress at Rolduc last year we 
left my RBT X2 at home and used the XA twin rig with a Belplasca as a 
back-up. (I like the RBT but it is a bit big for a travel camera).  One 
of Nancyís XAs slides from that trip was the 1998 Sydney Stereo Camera 
Club Slide of the Year.

Our XAs were twinned by a fellow member of the Sydney club who is a long 
standing member of PHOTO-3D.

To the best of my knowledge this type of conversion can only be carried 
out on the XAs - the ones with f2.8 lenses and aperture preferred 
automatic exposure control.  At any rate control of depth of field via 
the aperture is essential in serious 3-D photography and this is not 
possible with the XA2s.

As a light weight stereo camera with high quality lenses and "spot on" 
automatic exposure control, this pocket sized (for large pockets) twin 
rig is an absolute gem to use and has my vote as the best value stereo 
camera(s) available today.

Does everyone agree with this last comment?  " The XA twin rig, in 
master-slave configuration, is the best value stereo camera available 
today!!"

Ray


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