5D Mark III Skipping Frames at 10 seconds

[bluesteel105]

Hi everyone, I just installed Magic Lantern on my 5d Mark III, bought a Sandisk Extreme 64gb 120mb/s card but for some reason whenever I start recording RAW, it starts to skip frames at the 10 second mark. You can imagine my horror after just spending $315 on a memory card that should not be doing this. Has anyone else seen this? Advice? Greatly appreciated, thanks.

[bluesteel105]

I should also mention I'm averaging just under 60mb/s write speed and I'm trying to record 1920x1080. That seems a bit slow for the CF card I bought... Thanks for the help.

[chris_overseas]

I don't know much about that card but the quoted speed is likely the read speed rather than the write speed. According to this page on Amazon http://www.amazon.co.uk/SanDisk-SDCFXS-064G-X46-Extreme-CompactFlash-Memory/dp/B00EZE6V50 (assuming it's the same card?), the write speed is only 60MB/s so it sounds like it's performing exactly as per spec...

[ayshih]

Here's an ML benchmark of what is presumably the same card – http://www.magiclantern.fm/forum/index.php?topic=12630.msg121914#msg121914 – showing the >~100 MB/s read speed and the ~60 MB/s write speed.

But the important question is: did you spend $315 for something that's going for $100 on Amazon?

[jimmyD30]

Sandisk Extreme 64gb 120mb/s card...

Is that an SD or CF card? If SD, the write speed of the SD card data bus in the 5D3 is only 20MBps, you need to get a fast CF card (1000x/1066x) to record continuous 1080p. The CF card data bus is 100MBps.

If it's a CF card, then what resolution and frame rate are you trying to shoot at?

See here for camera write speeds: http://www.magiclantern.fm/forum/index.php?topic=6215.0

See here for card write speeds: http://www.magiclantern.fm/forum/index.php?topic=12630.msg121741#msg121741

[bluesteel105]

Thanks for the help everyone. Yes it looks like I got mixed up. The write speed is indeed 60mb/s so it's still not a fast enough card to do full 1920x1080. Thankfully I can return it and try something else. Mystery solved!