Blackmagic Forum

I am new to the world of BMD cameras. I have a small studio set up, where I am now using 3 BMD Studio Cameras, each with a Panasonic Lumix 14-42mm lens.
Intermittently, each camera (usually just one at a time) displays an issue that I can only describe as something similar to what you would see with poor tracking in a piece of analog video. At first I thought maybe this was a syn issue, due to the cameras not being gen locked, but I am using a BMD SDI DA which should (I think) be suitable for providing a reference signal to each camera. There are small horizontal lines that run through the frame and move from the bottom to the top of the frame. See the attached screenshot of a freeze frame with an arrow pointing to the problem area. It is a lot less distracting as a still then in motion. Has anyone else experienced this? Thoughts?
Thanks

No, a DA is not going to provide a reference signal. Yiu should gen lock the cameras. The scrolling line looks like a sync locking issue to me.
Cheers

Hi Denny-

Thanks for your reply.
It is a scrolling horizontal line, and, as you indicate, it seems that it would be a sync issue. But I don't think the issue is related to gen lock / reference signal, bc. I have tried using a sync generator going to the Ref In on all 3 cameras, yet the problem persisted. The problem was not introduced until I installed a Skaarhoj RCP (in place of traditional CCUs). And now, even after removing the Skaarhoj, I have the problem (it seems to only be happening on 2 of the 3 cameras, which is odd).

Thanks

Patrick

How are the camera cables being routed, are the two cameras with issues near any power source or their SDI cables near power cables?

I think I may have resolved the issue, but it doesn't make sense.

The way the cable routing bt. the cameras, switcher, and Skaarhoj is iss upposed to be set up, and the way I need it set up, is:
1) Each Camera Out to the switcher, and
2) The Skaarhoj RCP goes out to a BMD SDI D.A., which feeds the inputs on each camera.
3) I then was using an Aja sync generator to feed the Ref In on each camera, but I was still having sync issues.

I then removed the sync generator, and changed the camera's sync setting (which I previously didn't know existed) from "External" to "Internal" - still had the problem. But then I changed it to "Program" and voila - the scrolling line went away. I am not sure where it's getting the "Program" sync, nor why the issue was occurring on 2 of the 3 cameras...but for now, it works.

The cable is an interesting thought. Yes, I have the SDI cables and power cable tied together, for neatness. The power cable from each go to the same tri-power supply (IDX 300a), on the other side of a wall. If the problem comes back, I'll look into separating the SDI and power cables. Good thought.

Thanks

I guess it won't be the cabling.. If it is a steady line on the same place..

I can imaging if the sync isn't stable or looses sync due too connector not making proper contact or so it will jump on and off sync..

But with internal sync it should work steady without issues.. Did you reboot the camera between changing those settings? Might be that it keeps running sync until reboot in the old mode..

Now it takes a reference from the SDI signal and uses the SDI frame start to derive a stable source to use for syncing the sensor. If you now put the ref a few click negative the sync will be running in front of the frame buffer. This should eliminate most of the framebuffer from the Atem. And so running less delay in the chain.

With good shielded SDI cables and good power cables kept parallel to each other should not cause an issue. It is when the SDI/video and power cables intersect at angles that issues can arise. Sorry, didn’t think to suggest the sync menu settings. Glad you got it sorted.
Cheers

The "program" option locks the cameras to the Switcher output (the SDI IN of the studio cameras). The switcher now is the timing master.
The "Ref" options locks the cameras to the Genlock source. But I'm not sure if your Sync generator is feeding the Switcher as well. In the Genlock case, the Sync generator is the master and every one including the switcher has to get Genlocked.