First test: Canon EOS 5D Mark III @ 29:59 – does it drop frames between files? Not that I can see

by planetmitch2 Comments

Last week on twitter, I was asked about the new method of creating multiple 4gb files in order to achieve the new maximum video recording length of 29:59 on the Canon EOS 5D Mark III. My assumption was that we'd trust Canon to get this right and to have tested it, but of course we all know what happens when you assume!

I ran a test in IP-B mode (figuring that was the worst case since it is the lower compression option) and I had my Canon EOS 5D Mark III set up to record video from my iPhone with the Fostex AR-4i set up to record a voice memo.

It was interesting to note that in IP-B mode, the first ‘clip' was just over 18 minutes – which is what I expected to see since it compresses more than the old format on the Canon EOS 5D Mark II.

Max clip length and syncing audio

The request came in about syncing audio – and quite frankly, in the one test I did, it failed… so maybe someone else can try it (I'm swamped with work on the new 5D3 movie we have coming out and NAB next week). So here's the conversation that led me to run this test.

So here's the video record of my test: [tentblogger-youtube w07I4u4ExRI]

My results

As far as I could tell in this quickie test, there weren't any dropped frames between the two files and I was quite able to manually sync the audio. However, in this one test, FCPX failed to sync the audio. Additional tests would be required to see what the problem was, but I suspect it is a FCPX issue – not an issue with the files from the Canon EOS 5D Mark III or from the iPhone with the Fostex AR-4i.

I didn't try pluraleyes – but I would hope it does a better job of syncing.

(cover photo credit: snap from the video)


  1. I know when I owned the 5D MarkII, which I no longer do, it would at times record a glitch, and it would skip a frame. I talked to Shane H. about that and he had similar incidents. It didn’t happen all the time, but you never knew when was going to happen. I’m not saying that’s what’s going on with the new Canon, but personally, if i were shooting a take that needed to absolutely, positively be intact, I would never span that recording. Things like B-roll, no big deal, an interview, I wouldn’t span.

  2. After maxing out the near 30 minutes video limit, can you just insert another card and keep recording? Or, is there a time limit to let the camera cool down? A wedding ceremony is longer than 30 minutes.

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