[photo-3d] flash with twinned cameras

[boris@xxxxxxxxxxxx]

Doug:

I started with a twinned set of K1000 cameras, not too different from the
ME supers.  (In fact, my very first rig WAS an ME super and a K1000)

The solution to your problem involves first of all using just one flash on
one camera.  Then find a way to make sure that the non-flashing camera
opens its shutter first, and keeps that shutter open long enough for the
second camera (flashing) to have opened its shutter.  THen the flash will
fill both frames.

If you are triggering the cameras with a mechanical dual cable release, you
can adjust the release to make sure the flashing camera opens slightly
late.  Depending on the reliability of the release, you set an
appropriately slow shutter speed to reliably capture the flash on the
camera that opens first.  Experiment with different settings and
adjustments while looking through the non-flashing camera film gate (back
open, lenses wide open or removed), to see that the flash is filling the
whole frame reliably.  It should be possible to do this for shutter speeds
around 1/4 to 1/15, maybe even 1/30.  Faster shutter speeds get too close
to the single camera synch speed, and mechanical variability will start to
spoil some of the shots.

My twin K1000s have worked well with a similar setup for several years.
(In fact through some beginners magic, when I first started using them with
flash, being oblivious of the potential problem, my first set of films came
out fine!!  Then they started going bad after that first session, forcing
me to learn the theory and mechanics of shutters, sync. etc.)

Note: the cabling for the release (mechanical) should stay physically in a
constant configuration.  Don't let the release flop around randomly.  When
the cabling shifts position, the releases will synch differently.

If you are synching electrically, you just have to figure out which camera
is a little slower to respond, and put the flash on that one.

If you are not using a twin release, you might even be able to use the two
finger method (for speeds around 1/4 second this might work).  Trouble will
be with ambient light affecting exposure a lot, and asynchrony creating
rivalry.

Boris

________________________________________________________________________
©2001 Boris Starosta, stereographer   boris@xxxxxxxxxxxx
Dynamic Symmetry, LLC                 http://www.starosta.com
usa - 804 979 3930                    http://www.starosta.com/3dshowcase




 

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