On 13 Nov 2001 04:40:43 -0800, Paul Rubin wrote:

>"Jim Hoyle" writes:
>> I'm planning to do 3d motion capturing (with white balls) with three Sony
>> DV-camcorders placed in 120-degree intervals. Will this work?

>If you mean will the cameras stay in sync with each other, the answer
>is they will drift after a while. To keep them in perfect sync you
>need a feature called genlock which is only found in professional
>cameras. If you don't need to shoot continuously or if you can stand
>a little bit of drift you're probably ok with consumer cameras. The
>speed of the cameras is controlled by quartz oscillators in the cameras,
>similar to a digital watch. If you assume 1 sec/day accuracy (say one
>camera is +1 sec/day and the other is -1 sec/day), then they can be
>2 sec apart after 24 hours, or 1/30 sec apart (1 frame apart) after
>1/60th of 24 hours = 24 minutes. That might be ok for your purposes.
>Genlocked cameras will stay sync'd to the same scan line.

I have run about 6 different Sony Mini-DV camcorder
models (plus multiple samples of the Sony models, plus
one Panasonic model) for 1+ hours together without losing
synch even a frame with any of the cameras - without
genlock...