[photo-3d] Re: slr twin rigs

[JNorman805@xxxxxxx]

Peter Davis writes:

<< However, twins have 3 potential problems, as I see it:
 
 1) Difficult to get exact synchronization in all cases.
 
 I believe people have bought two of the Canon remote shutter cables and 
spliced them together.>>

Yes. that's what I did with my Casnon Rebel rig. Synch is perfect about 85 - 
90 per cent of the time.  When it's off, it only shows up in  flash shots.
 
 <<2) Difficult to get normal or near-normal lens separation.
 
 To reduce the lens separation, it seems like turning one camera upside down 
would help.  Anyone know of a bar that could be made to work like this?  That 
would be very useful for twinning in general, I think.  Anyone know what kind 
of lens separation could be achieved this way?
 
 Another option is to put the cameras base-to-base.  While I'd like the 
option of doing this quickly and easily in the field, I think I prefer a 
horizontal format for most of my shooting.>> 

Look for pictures of my vertically oriented twin rig, mounted base-to-base, 
on Paul Talbot's cyber encyclopedia page.  Spacing between lenses is about 75 
mm center to center.  I use 35-80 mm zoom lenses, so at just about any fl 
past the so-called "normal" 50 mm, the 75 mm spacing is so-called "normal" 
stereo.
 
 <<3) Potential horizontal and vertical alignment problems with commercially 
mounted slides.
 
 As for the vertical alignment, I think this can be corrected by shaving down 
the bottom of one of the slide mounts.  Any suggestions on how to do this?
 
 Another option is to remount the interesting pairs in 41x101 mounts, but 
that loses some of the commercial mounting advantage. >>

Forget about commercially mounted slides having perfect vertical alignment.  
Between the vicissitudes of commercial mounting and the difficulty in getting 
perfect alignment between tour two SLRs, you will simply have to do your own 
mounting.  I use 7-perf Gepe mounts, giving me enough leeway to to move the 
chips up or down as needed, then when I am satisfied with the relative 
alignment, I join the two slides together with a 5/8 incha spacer between 
them and project them from the rear channel of a TDC 116 slide carrier.  
Where the vertically mounted twin SLR rig really shines is for making printed 
stereo view cards.  It's VERY easy to cut and align side-by-side prints 
properly.

If you're looking for an easy fix to all your stereo problems, a vertical SLR 
rig just aint it!  But its advantages are many, in my opinion, so the 
disadvantages are outweighed.  All of this is just my two cents, of course, 
and others are free to disagree.

 

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