A fine point about XF and Cinema EOS Multi-cam Time Code

[Pete Bauer]

Just passing along a little multi-cam tip that applies to the XF cameras, as well as the C300 and C500. This doesn’t apply to the C100 since it doesn’t accept TC in.

THE MYSTERY:

I do a lot of multi-cam XF shoots. On occasion, I’d find that one camera would be off by a number of frames after synchronizing by TC on the timeline. To my surprise, the same thing happened recently with a C300 added to the mix; it was off by 5-6 frames from the other 3 cameras in that shoot.

That finally prompted me to dig into the issue. I recalled that I’d briefly powered off the C300 between jamming time code and recording the event. Wouldn’t seem a big deal since ALL of these cameras’ user manuals (XF and “C” cameras) have a note that says:

As long as the built-in rechargeable lithium battery is charged and you selected the [Free Run] running mode, the time code continues to run even if you disconnect all other power sources. However, this is less accurate than when the camcorder is on.

The plot thickened when I was able to verify that in earlier instances, the XF that was slightly out of sync was one that was turned OFF instead of being put in Power Save mode while awaiting the event.

THE ANSWER:

That last sentence (“…this is less accurate…”) finally caught my attention. I contacted Canon USA and they kindly gave me a very logical and complete explanation:

When the camera is turned off, the internal time-of-day clock continues to run. However, there is no power running to the time code generator and it therefore is not running.

The camera re-establishes time code when turned on again by analyzing the internal clock and comparing where the time code was when the camera was turned off and computes where the time code should be when it is turned back on.

The catch is that the internal clock is only accurate to the second but not to the frame, so when the time code is re-established it may be off by any number of frames in a second.

To keep your cameras frame-accurate, you can do any of the following:

• Leave the camera powered ON.

• Use Power Save mode (XF cameras) or the equivalent Lens Exchange feature (C500 only). Canon confirmed that power to the TC generator will be maintained. Note that this option doesn't apply to the C300. It is either ON or OFF; no Lens Exchange mode.

• Attach a Lockit Box which is a separate time code generator that will override the camera’s time code.

• Each time the camera is powered back on, re-sync the time code.

I'm really glad to better understand to ensure all my cameras stay frame-accurate. Many thanks to our friends at Canon USA for solving this little mystery!