Raw Recording stops after 3 secs

[HypnoticSens]

Hi,

I just installed ML on my Canon 5D mk iii but when I shoot in RAW, recording stops after 3 seconds with the message "Skipped Frame. Stopping". (in 1920x1080 / 23.976fps)
I guess the issue come from the writing speed of my SD card, but I'd like to be shure of this because my SD is quite fast, it's a Lexar Pro x1000 150 Mb/s and I though it was enough for RAW.

So my question is : Is using a Compact Flash card obligatory ? Is there a real big différence between my SD card and a CF of same power that can make RAW recording works better ?
Because I don't want to buy a quite expensive CF if the result is the same 

Thanks ! 

[Walter Schulz]

my SD is quite fast, it's a Lexar Pro x1000 150 Mb/s and I though it was enough for RAW.

No ML enabled cam supports UHS-II interface. You're stuck in UHS-I compatibility mode.
Doesn't matter in this case because
a) Card's write limit in UHS-II is about 96 MByte/s* and therefore on par with fastest UHS-I cards available. In UHS-I mode card will do about 80 MByte/s
b) the cam's card interface is limited (at time of writing) to about 25 MByte/s (theoretical). In real life you will be lucky to see write transfers going above 20 MByte/s

Running benchmarks in cam and with cardreader would have answered your question, too.
http://www.magiclantern.fm/forum/index.php?topic=20454.0#post_C21

Is there a real big différence between my SD card and a CF of same power that can make RAW recording works better ?

21 MByte/s : 110 MByte/s (give or take)

*: Or below, depends on card size/generation. See www.cameramemoryspeed.com/reviews/sd-cards

[andy kh]

So my question is : Is using a Compact Flash card obligatory ? Is there a real big différence between my SD card and a CF of same power that can make RAW recording works better ?

Thanks ! 

CF Card is neccessary  for your camera model to shoot full HD or higher resolution

[HypnoticSens]

Ok !  Indeed, I didn't consider that UHS compatibility...   

So if I understand, a CF card is less limited by the 5D than a SD is ? That's why I'd better use a CF rather than a SD no matter how fast SD is ?

[DeafEyeJedi]

Just keep it simple. Run ML on SD. At least get a fast CF (1066x) for recording RAW on it. Happy times!

[Walter Schulz]

4 options for 1066x CF:

Komputerbay 1066x
Lexar Professional 1066x
SanDisk Extreme Pro 160 MB/s
Toshiba Exceria Pro 1066x

UDMA-7 compatible cardreader is a must. Komputerbay may get damaged permanently (destroyed!) if used in non-UDMA-7 readers.
And SD-to-CF adapter cards are not an option. Most are crap and the non-crap one's can't do high-speed needed for high-res RAW video.

[kichetof]

Lexar Professional 1066x

To be sure, ≥ 32Gb (see the write speed for 16Go)