Twin Camera Shutter Synchronization
Disclaimer: This article is provided for information only. You must assess your own abilities to
perform the work described - neither the contributors mentioned nor Rocky Mountain Memories assumes any liability
for any damage you may do to your camera while following these suggestions!
When using two cameras for 3D photography, it is desirable to "synchronize" the timing
of the shutters in both cameras. There are two goals for shutter synchronization:
- Reduce or eliminate differences between the two images due to subject
- Synchronization of the shutters closely enough so that an electronic
flash (with it's very short duration) will occur when both shutters
Perfect synchronization is, of course, not possible. Various methods of
synchronization can be used, depending on the trouble you want to go to
and how closely you require synchronization. In general, these are in
order of increasingly better results:
buttons at once"
but poorest and most variable results. Works OK for
subjects with relatively little motion.
||Not good enough
for use with electronic flash, except with very
slow shutter speeds.
||This can be either two
shutter cables fastened together, or a
commercially-avaiable twinned cable. Inexpensive, but
relatively poor synchronization. In commercial units,
some adjustment of shutter timing is possible.
||Syncronization may not
be good enough for electronic flash.
||Uses a "bulb" shutter
activator with a "tee" in the air line.
||Good for cameras up to
several feet apart.
||Most accurate of the
||A storage scope is suggested
||Best synchronization is
||Requires cameras with an
electrically activated shutter
If you have two cameras with electrical shutter buttons, the simplest method of
synchronization may just be to buy the remote shutter buttons offered by your
camera manufacturer, and wire two of them together. Details will vary by
The drawback of this approach is that there can be some interaction between
the electrical systems of the two cameras, especially if the battery on one
is at a lower voltage than the other. This may cause poor triggering, and
in some cases one camera will refuse to fire. This may be cured with the
following circuit, which uses diodes to isolate the two cameras' electrical
systems (this schematic thanks to Marty Hewes):
Germanium diodes are highly recommended, because their forward voltage drop
is much less (typically 0.2 - 0.3 volt) than silicon diodes (typically 0.7 volt).
The switch is an external push button that fires both cameras - each camera can
still be fired individually by the camera's own shutter button, even when
Note: This diagram assumes the negative terminal of the camera's battery
is connected to the chassis. If not, the diode polarity shoud be reversed.
Paul Baker suggests the following enhancement to the above drawing:
The advantages of this setup are:
- No external push-button switch is required.
- The shutter on either camera can be used to trigger both cameras.
- This requires some camera surgery, as you now break the original connection between the camera
shutter button and the shutter activator inside the camera, and insert the diode
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