Occasionally we use our EX3 in multi-camera configuration with older SD cameras and a switcher. The camera has S-video and composite BNC "monitor" outputs in addition to the SDI output. We are recording SD 4:3 on DVcam.
Since we have fairly long cable runs on these shoots, S-Video isn't a particularly attractive option for us. So we are left with either using the composite "monitor" output, or using the SDI output into our switcher (Sony DFS700). The problem with SDI however is that it's not synced. We've been told that a composite black burst into the EX3's SDI reference may actually sync the camera. It sounds like a cute fix, but frankly I'm a little cautious about even experimenting with this solution. Any opinions? Also are there any opinions on the quality of the composite video output? It seems significantly inferior to the S-Video output, more so than one would expect.
You must already own the switcher, but some, including the Panasonic 400A which I own have built in frame shaker to sync the incoming signals. At the very least, if your does not have this capability, you could use an outboard frame shaker. i think the AJA FS1 will do it and there must be other less expensive options.
I've done pretty much exactly what you are describing with the very same switcher and two EX3s, and we used the black burst out of the switcher into the Ref In on the cameras to sync them. The composite camera outputs were used for monitoring, and the SDI outs went into the switcher. Camera output was downconverted to SD, center cropped to 4:3, and the switcher output was recorded to DVCAM. I didn't see much of the finished product but of course using the SDI will be better than composite or s-video. I'm not sure why you'd worry about using the black burst for sync, that's what it's there for.
I'm not all that experienced working with SDI, the EX3 manual seems to specify a SDI reference signal input to the camera's genlock port. But if my reading of Atticus's response is correct, an old fashioned analog black burst will do the job. So we will definitely try this approach.