July 8, 2015 at 10:24AM, Edited July 8, 10:24AM


1000x CF cards - Raw video - HELP.

Hey guys -

So I've been doing A LOT of reading on the interwebs about .raw video recording -

Shooting on a Canon 5D Mk II magic lantern nightly build "July02.5D2212" - I'm looking at buying a CF card which will cope with the write speed of shooting .raw 1920x1080 (or as close as you can get)-

I am absolutely flummoxed by the information I'm reading
I feel like a badger being taught an ancient language - Imagine how that would turn out.

Anyway - I simply would like you guys to recommend a good card that you've been using for .raw video on the mk ii/iii

I've found a Lexar card that seems to have some good reviews on the web/amazon/ebay - however your 50 cents is always always appreciated.



There are lots of threads on the Magic Lantern forums about the 1000x CF cards that people have had success with. It really sounds like you just have to pick a card that is popular for shooting 5D RAW, and see how it all turns out.

B&H Photo Listing of their 1000x CF Cards

Myself, I prefer to buy the SanDisk Extreme Pro cards because they are ALWAYS fast and they usually come with a life-time warranty. ( if you don't abuse them, SanDisk will replace them for free if they stop working properly )

Also, if you are using a Windows computer you should get yourself a free copy of the ATTO disk benchmark utility, which is a great way to find out the REAL read and write speeds of any of your memory cards. Just make sure you are using a USB 3 card reader connected to a USB 3 port on your computer, as USB 2 readers and ports are too slow to properly benchmark your memory cards.

I ran the ATTO test on a $20 Silicon Power Blaze B30 32GB USB key that I own, and saw that the top write speed of this key was about 40 MB/sec but the read speed was about 225 MB/sec. I knew that this USB key was fast to read, but never imagined it was over 200 MB/sec.

With my 64 GB SanDisk Extreme Pro SDXC cards I'm getting read and write speeds of 80+ MB/sec, and with my 128 GB Lexar SDXC cards I'm seeing average read and write speeds of 85+ MB/sec. ( all of my other SDHC cards, which I now only use for audio recording, are about 20+ MB/sec read and write on the ATTO benchmark )

July 8, 2015 at 5:48PM

Guy McLoughlin
Video Producer

Please forgive my ignorance as I'm only trying to learn;
Is 80MB/sec equivalent/greater than 1000x on a CF card - I've googled but can't find much anywhere what the 1000x (or whatever numeration on the CF card) equates too

David David

July 9, 2015 at 7:10AM

>>>Is 80MB/sec equivalent/greater than 1000x on a CF card - I've googled but can't find much anywhere what the 1000x (or whatever numeration on the CF card) equates to

It's easy to get very confused with all of these speed ratings for memory cards, but I'll try and break things down into some simple statements... :-)

The 1000x CF card speed rating is based upon the ancient standard CD-ROM playback speed of 150 KB/sec. God knows why they chose this to base the standard on, but a 1000x CF card speed rating is equivalent to...

1000 x 150 KB/sec = 150,000 KB/sec = 150,000 / 1024 = 146.48 MB/sec

Which is about the same data transfer speed as a typical 7200 RPM hard-drive you would find in a modern computer.

The problem with this 1000x CF card rating, is that it's based upon the READ speed of the memory card and NOT the WRITE speed of the card. ( the WRITE speed is far more important when recording data than the READ speed, because if the card can't WRITE your data fast enough to it's memory storage then your data gets lost or corrupted )

When you are shooting very high data-rate video you are ONLY concerned about the card being able to WRITE your data as fast as your camera spits it out.

The other big issue with this 1000x CF card speed rating is : How fast can your card WRITE data continuously ?

Some cards can write data very fast, but only for a few seconds then it starts to slow down, and again you end up with lost or corrupted data.

I noticed that with the SanDisk Extreme Pro CF cards they list a maximum READ speed up to 160 MB/sec, and a WRITE speed up to 150 MB/sec, but this does not guarantee a continuous WRITE speed of 150 MB/sec.

Looking at the details on the BH Photo web page for these cards, SanDisk states that these cards have a VPG-65 (Video Performance Guarantee) specificationof a minimum sustained write speed of 65 MB/sec. So they guaranteed that the WRITE speed will never go below 65 MB/sec WRITE speed.

This may sound kind of slow, but you will find that other card manufacturers either don't list a guaranteed minimum WRITE speed, or that they don't list anything faster than this.

Again, I would suggest that you pick a 1000x CF card ( this translates to 146 MB/sec or faster data transfer rate ) and do your own tests to see if the card works with your camera.

Personally I would start with a SanDisk Extreme 160 MB/sec card, and then benchmark it with the ATTO utility to see what the real READ and WRITE speed is for this card, and then try shooting some RAW footage with your camera.

July 9, 2015 at 8:29AM

Guy McLoughlin
Video Producer

You're brilliant man - thanks for answering so concisely :)

David David

July 9, 2015 at 10:22AM

My 1000x cards that I have used for RAW on my 5D3 are fairly inconsistent. In my experience the supposed speeds of the cards are greatly exaggerated. That being said, don't fear because of the option to use "card spanning" which records on the CF until the buffer is full, then switch to the SD, then back to the CF, etc. It effectively combines the speed of the CF card and the SD card (the SD unit is bottlenecked at around 20MB/sec though). I have Lexar 1066x cards as well as Transcend 1000x cards. I just always keep the card spanning feature turned on for safety. For shorter shots you can get away with not using card spanning but if you want continuous recording for longer takes just use card spanning.

My Lexar 1066x card write speed was consistently 110MB/s+.
My Transcend 1000x card write speed was consistently 85MB/s+.
Then I tested my old Transcend 400x card for fun. It wrote at 60MB/s+. Combine that with 20MB/s from the SD card and you're able to almost record 1920x1080 raw (something like 85MB/s at 24fps).

Different buffer sizes will impact the write speed on the camera, of course. These speed tests were done in-camera with Magic Lantern on my 5D3.

Also, on my 1000x+ cards the READ speed was 150MB/s or more, which is what the rating is based on.

Just remember to have tons of hard drives and keep your camera cool and have fun!

July 9, 2015 at 3:23PM, Edited July 9, 3:36PM

Jeremiah Kuehne

I've just been using a Scandisk 32gb 160MB/s and to no avail, however I think it's an internal problem - Trying to shoot .raw on the highest resolution closest to full HD.
I get to about 9/10 seconds and it stops recording.
When looking at the card also there is no footage, but what can only be described as a glitchy screen.
I don't think it's the card, pretty sure it's my mk II.

July 16, 2015 at 1:06AM


Didn't read all of the comments but I'm using KOMPUTERBAY cf cards and I'm able to record the max reso in 2:1 aspect ratio. I haven't recorded anything over a minute yet and I think it won't handle it in this resolution/aspect ratio. Good bang for your buck nonetheless!

July 21, 2015 at 2:34PM

r b

I've been using a Transcend 32GB CF, 1000x card without any problems.
shooting at 1920, have recorded continuously for over a minute. Never really tested how long it records continuously but it has not let me down so far.
my takes have never been more than about a minute long.

July 7, 2016 at 3:25PM

Saad Khan
Director/ Cinematographer

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