Shooting with multiple EX Cams
 

Had the opportunity to run a 5 camera shoot. 4 EX1s and an EX3. Set everything to fire off of one remote . . .the fact that when you power cameras down remote functionality goes away was a pain in the ass. Had all the clocks set to 00:00:00, started them with one remote. Used the remote to start record simultaneously. Shot sync marks with all the cameras.

Conclusion: It doesn't work. At the sync mark all the timecodes are different. Close but different. The start times are varied in code also as well as the physical time. Sounded like a good idea that should work but it doesn't. Luckily I had BB ref going into EX3 and was synced with the audio guy pulling a 12 channel mix for edit. AND shot the sync markers.

-Tony

Are they all on the same type of timecode? free run df or ndf?

I set the time code based on the camera clock, which is drop frame.
-T

I thought camera clock meant the camera's internal clock - as in 17:11:08 (5:11:08pm)

The camera clock writes what looks like drop frame free run time code.
-Tony

You will never have true locked time code, unless they are all genlocked to a source. Even TC to TC via BNC will miss eventually, unless genlocked.

Correct. I doubt that the EX1 has a Genlock In and can be slaved to a TC source.

Yep, EX-3. Not 1

And that TC is as precise as it is generated by a xtal driven electronic circuit.
The better (more precise) the xtal, the more precise the TC. Deviation from
ideal output is measured in ppm (parts per million) and shows the quality of
the xtal.
I doubt if Sony would publish the specs of its TC generator.

Yeah, yeah the EX3 was totally genlocked. I just thought that firing everything from the remote would give me 5 cameras with the same timecode. I mean it seems like it should work . . . push the button and everything starts at the same time, clocks and roll. My point is that it doesn't. Maybe it shouldn't work but with today's new technology, it doesn't hurt to try.

Thanks for your input,
Tony

What is the moral of Tony's story?

Take only EX3s and genlock them ;-)


My poor man's solution: I distribute the same sound to each and every camera so that it can
record picture and that sync sound, preferrably the out signal from the PA's mixing console -
and I edit according to the sound. Every cheap camera can contribute to that scheme.

P.

An alternative is to use a switcher. I have four EX1s purchased for use in a camera chain before there was an EX3. I'm getting very decent results. I try to keep one camera wide all the time and I record to the SxS card on that camera just in case there's a mistake that needs covering later. Most difficult for me is painting the cameras. I use auto-white and then have to tweak.

Marc,

Why would that be preferable to trying to pull a good white balance with each camera on a common subject prior to the shoot and keeping it all manual?

I ask this because I recently did a shoot where I pulled a good white balance in a low-light environment and without thinking set the camera to Auto WB. Over a few seconds (without me noticing), everything slid away from white and all my whites ended up cream-colored.

I intend to use Auto WB exremely selectively, if at all.

In practice, that's what I do. The similarity among whites with EX1s is VERY good when you white balance manually. That said, if you have one or more cameras with different circumstances, a camera shooting near a window you can't shutter for example, tweaking is still required. And when I have to tweak I really wish I had a CCU.

It's important to realise that the crystal primarily controls the frame rate of the camera, and the TC is directly derived from that - one frame = one TC reference.

Which is why you can't simply feed one cameras TC into another camera without genlock, the TC frames would "slip" relative to the actual video frames.

Even if the absolute TC figures were different, genlocking cameras will ensure that the offset remains constant throughout any recording.

I think Peter Kraft has the best fail safe by putting an audio track back to each camera this gives a good sync reference when things fall apart. I am editing a client's camera job where production recorded to 8 track hard disc and had no sound at all on some material! The grand plan was to sync it up later without having accurate time code on Z1s. There is always a challenge in life.

Clapperboards still have a place
 

On a recent shoot with 4 EX1's, since we couldn't genlock the cameras, we used a plain old clapper board. This let the editor sync all the cameras precisely in post. A bit more work, but at least it worked. Timecode can be off, regardless of the source and it is more precise to use a sync mark from a clapper (analog or digital) for perfect sync. The clapper board also gives you scene and take info (if you bother to include it) that is not necessarily there in the TC, something that editors appreciate.

Sigh . . . I guess you're all missing the point. We know about genlock and reference. The point was that if you could start all the same cameras at the same time running the same frame rate the images should match. Hey the timecode may be off but who cares . . . this is the new paradigm. Yeah I know all about broadcast do's & don'ts but if you had told me five years ago that we'd be shooting full hi-def resolution to SD cards and Kensington adapters, I'd a laughed out loud.

So back to my point. Starting 5 cameras rolling with one remote doesn't work. Will it work in the future as technology advances? You can bet on it!

Thanks for the discussion,
Tony

Ha! Good point, Tony!

IR remotes are not the way to do it. There are too many other factors that can affect IR remote performance, ambient light, distance, obstructions, reflections etc. Even if you use the very best broadcast cameras they will still drift.

In my recent 3 EX1 project, just before we started shooting, our timecode was set to free run, and reset "simultaneously" on "one, two three..."

It was good enough to perfectly synchronize all 3 of them, using the loud sound at the beginning that all cameras recorded. In Vegas, once I aligned the three tracks basing on this sound "peak" in the sound wave, I had all remaining events synchronized for several hours of recording (the rehearsal, and the main performance that we shot).