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6D needs a fast enough SD card for RAW @ 4.5FPS


After reading some reviews about issues with (secondary) SD card controller in famous 5D MarkIII camera, I decided to test the one in my new 6D camera.

Speeds tested with same composition and lighting (poor tungsten), same frame settings: exposure 1/200 @ f/1.6 on iso 800, object of shooting was my window mounted room air conditioner (LOL, I know ha ha!):


Since I already spent some time on preparing the information for myself, I thought I'd share it here 🙂

File sizes with approximate write bandwidth at camera's max 4.5FPS (continous shooting mode):
RAW 20M 5472x3648 - file size of 22,814 KB ~ 100.2 MB/s
mRAW 11M 4104x2736 - file size of 16,581 KB ~ 72.9 MB/s
sRAW 5.0M 2736x1824 - file size of 11,228 KB ~ 49.3 MB/s
L high 20M 5472x3648 - file size of 5,303 KB ~ 23.3 MB/s
L medium 20M 5472x3648 - file size of 2,488 KB ~ 10.9 MB/s
M high 8.9M 3648x2432 - file size of 2,463 KB ~ 10.8 MB/s
M medium 8.9M 3648x2432 - file size of 1,090 KB ~ 4.8 MB/s
S1 high 5.0 2736x1824 - file size of 1,470 KB ~ 6.4 MB/s
S1 medium 5.0 2736x1824 - file size of 643 KB ~ 2.8 MB/s
S2 2.5M 1920x1280 - file size of 766 KB ~ 3.4 MB/s
S3 0.3M 720x480 - file size of 155 KB ~ 0.7 MB/s
*approx write bandwidth calculated with formula (FILE_SIZE_KB * 4.5)/1024, results in MB/s rounded up

from observation it seems that file sizes can grow by around extra 50% for JPG (Large high quality) or sRAW at certain composition & light scenarios.

Maximum file sizes I've seen were 27,800 KB for RAW (calling for over 122 MB/s write speed in 4.5FPS continuous shooting mode) and nearly 8 MB for Large JPG in high quality (equivalent of 35.1 MB/s in continuous shooting mode). Former one was no go with Sandisk Extrme SD (bus afte 13 frames), the latter went through no problem for around 30 secs (over 130 frames).

phew ... bottom line is I was able to shoot continuously all kinds of JPG frames infinitely (tested up to 30 secs) with my Sandisk Extreme 45MB/s SD card ... however that's way too slow for any kind of RAW frames - literally after 13-16 frames you will see a "BUSY" message and shutter speed will drop to 0.9FPS until you release the shutter button and let the camera save the buffer to card, then you can repeat.

I was actually thinking of buying the fastest SD card on the market I could find, but gave up after I came back finding only Sandisk SD Extreme Pro cards rated up to 90MB/s write speed, they are probably good maybe up for mRAW, but still not enough for RAW.... hoping the faster SD cards get developed some time in future as I really enjoy pure RAW mode ... and sometimes want to do a series ofshots formorethan 13 frames 😉

Do I need continous shooting mode daily for over 13 frames each time? no, not at all, but someone might and if you do then your only real option is 5DMIII camera (with similar full frame sensor) and a blazing fast CF card that could support infinite shots up to card's capacity.


Good news is that the SD cards are working great (as advertised) in 6D camera! 🙂


hope it helps.

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