Canon 5D Mark III with Canon EF 24-70mm f/2.8L II USM Zoom LensHave you ever had your Canon 5D Mark III freeze after capturing a video up to the time limit? Apparently the Mark III has issues with certain CF cards, regardless of speed, and cameras have been locking up and losing footage. This seems to occur most often once the camera reaches the 30 minute mark. Since the Mark III records to a FAT32 file system on CF cards, the max file size for each clip can only be 4GB, which corresponds to about 12 minutes. Once the camera hits 30 minutes, certain cards have caused the camera to lock-up, losing the previous 12 minute clip in the process. Now we have a petition from users who have been affected hoping for a fix from Canon.

[Update]: a1ex from Magic Lantern sent me some interesting information, and possibly a way to see if there are specific cards that have issues:

It may be related to this bug that I've found in 5D Mark III on file i/o side:

I would like to ask the users who experience this bug to try to run the alpha 3 ML - it includes a card test at startup, and will refuse to run if the card is incompatible. I'd like to see if there is a connection between these problems and my bug.

Here is the petition letter to Canon, sent to me by Max, which was only started recently:

You have probably heard of many customers globally having problems with Canon 5Dmk3 camera freeze and lost files, both video and stills. If not, this is just one of quite a few forums discussing this for your reference -

We need to draw your attention to us needing you to get it fixed ASAP. 
As simple as that - admit it exists and find a solution, please.
We can't afford losing our files any longer and using the gear that have a problem that is intermittent.

This is one of Canon's official responses about the issue:

We are not aware that there is an issue with these Sandisk cards within the camera. If you suspect it to be the cards, I would recommend trying a different brand and or size to see if the issues persist. We are not aware in advance when new firmware and or changes are coming to the camera. Anything like this would be announced on the Canon EOS web site. I would say that if another card causes the same issue you would want to send the camera in for service. Currently we are not able to recommend one specific brand of cards over another. We apologize for any inconvenience that this may cause you at this time.

There is no reason why the cameras should be experiencing these issues. I was using only Sandisk cards during my time with the Mark III, but I never recorded more than a few minutes at a time, so I couldn't have replicated the problem. It seems that this is an intermittent issue, so that could be one of the reasons why there has not been a fix issued so far.

I also think this could be a good forum to talk about the problem, and see who else has been experiencing it and how widespread it actually is. If the percentage of people who have had issues is low enough, Canon may not see the point in spending time and money to fix it. However, people have bought this camera expecting to use it as advertised, and that has not been the case for many.

If anyone has more information about the problem, or would like to contribute their own story, feel free to share in the comments. If you have been affected, you can find the petition using the link below.