gentSTEREO-proSDM allows an external flash to be employed with a stereo pair of cameras. Use this procedure to set up the flash delay using the 22turn adjustment beside the flash output.

1. Choose a testing environment where the flash illumination will be obvious, even with ambient lighting at 1/60 second shutter-speed this may be difficult.
2. Turn-on both cameras and set a review time (in Canon menu) of a few seconds and select the smallest image size to save card space.
3. Set flash to 'Off' and in Tv or manual mode set the shutter-speed to 1/60 sec.
4. If your camera does not have these modes, in SDM 'Bracketing/Override' menu set Tv override and an override shutter-speed of 1/60 second.
5. Carefully rotate the delay adjustment on the gentSTEREO fully counter clockwise* until a stop is reached. This is easier to detect if you use a very small screwdriver (such as a watchmakers) to make the adjustments. Beyond the stop there is a friction brake or clicking noise.
6. Each half-turn of the adjuster increases the delay before the flash fires (after switch release) by about one millisecond.
7. Connect your external flash to the gentSTEREO using a 2.5mm mono jack plug and connect the unit to the cameras using two USB leads.
8. Turn on the gentSTEREO.
9. Quickly press-and-release the red button, both cameras will auto-focus.
10. Press the button again until both blue LED's are lit and release button after a short delay.
11. The flash should fire and you can view the results during the couple of seconds of review time. The flash will not be captured at this stage, as the delay after button-release is zero and all supported cameras are known to delay tens-of-milliseconds before capturing the image.
12. Rotate the adjuster half a turn clockwise* (to increase the delay) and repeat the procedure. Continue adjusting until the flash is captured by both cameras. Depending on your camera model, you will need to make 10 to 30 half-turns before capturing the flash.
13. Double the shutter-speed on both cameras and test again. Repeat until the flash is not captured by one or both of the cameras.
14. Make an adjustment of a quarter turn (about 0.5 milliseconds) in both directions and test again.

With this procedure it is possible to temporarily synchronise at far higher shutter-speeds than normally required.

After you have achieved the fastest-possible setting you should then set both cameras to a more realistic speed (such as 1/125 or 1/250 sec) that prove dependable from day-to-day. Take a series of shots at that speed and if there are any 'misfires' make a small adjustment to the delay.

* Shipments made before March 2010 use REV A design where the rotation of the 22turn adjustment is inverted from the current production. These instructions are for the more logical rotation in current production.