Compact Flash Card for Canon 7D


What you must look for when buying a compact flash card for Canon 7D.

A question that frequently pops up when people want to shoot video with their Canon EOS 7D is regarding the required minimum speed of the Compact Flash card. Card speed is usually specified in “x” ratings, e.g. 8x, 20x, 133x. This is the same system used for CD-ROMs and gives the data rate as a multiple of the data rate of the first CD-ROMs (i.e. the data rate of an audio CD). The base rate is 150 kB/s, so for example, 20x = 20 * 150 kB/s = 3.0 MB/s. The following table lists some common ratings and their respective maximum transfer rates.

Rating = Speed (MB/s)

6x = 0.9 MB/sec
8X = 1.2 MB/sec
12X = 1.8 MB/sec
20X = 3.0 MB/sec
25X = 3.8 MB/sec
30X = 4.5 MB/sec
32x = 4.8 MB/sec
40x = 6.0 MB/sec
60X = 9.0 MB/sec
66x = 10.0 MB/sec
80X = 12.0 MB/sec
90X = 13.5 MB/sec
100x = 15.0 MB/sec
133x = 20.0 MB/sec
150x = 22.5 MB/sec
200x = 30.0 MB/sec
266x = 40.0 MB/sec
280x = 42.0 MB/sec
300x = 45.0 MB/sec
433x = 65.0 MB/sec
600x = 90.0 MB/sec
666x = 100.0 MB/sec

For Video, Canon recommends at least a 8MB/sec card (60x). But since all cards do not necessarily perform at their indicated speed, it is recommended to get a faster card. A 133x would be both safe and cheap. The money you are saving by not buying a more expensive cards, would be well spend getting a higher capacity card.

Personally I have been using several Kingston Elite Pro 32GB x133 without any issues, but your mileage may vary.

Important note:

This card works absolutely fine. If you have speed issues with your card (or if you have purchased it off eBay, you might want to read this article: How to spot a fake memory card

Useful Links

The Memory Card Performance Database shows you how most cards on the market perform.

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  1. Edwin says

    Hello Jan,
    I came across your comments regarding Compact Flash card used for video recording on a Canon EOS 7D. I intend buying an EOS 7D and wanted to know what CF card I will need that will handle the video recording.

    I am a bit confused and maybe my thinking is somewhat unclear. The way I see it is that if I shoot a video in 1080 high definition (1920 x 1080) then this equates to 2.1 MBytes per frame and there are 30 frames per second. So this equates to 63 MBytes per second being saved to the card. This means needing a card with a speed of at least 433x. So how are Canon recommending 8 MBytes/sec as being adequate?

    With my lack of knowledge on this subject, am I overlooking something?

    Look forward to any advice and clarification.


  2. says

    Hi Ed,
    I am by no means an expert on video formats and compressions but I don’t think you can translate the ‘photographic settings’ to ‘video settings’. Video cameras, in general, use codecs that compress image sequences, so in fact when you have let’s say a 30fps movie, the camera does not literally store 30 frames at 1920*1080 but determines a number of keyframes and uses interpolation algorithms between those keyframes. I think, but don’t quote me on that, that the number of keyframes stored is closer to 4. Since all the calculations are done by the camera’s processor, the actual writing speed can be much slower. So yes, 8MB is actually enough. I have a x133 card and haven’t experienced any issue so far. The 7D has a buffer indicator that only appears if the camera can’t write fast enough to the card. I have only seen that indicator once and at its lowest level and only for a second or two. So a x133 works absolutely fine. I picked x133 because it was slightly more than the double of the recommended 8MB/s because you have to account to different qualities in the cards. In my experience anything better than 20MB/s is more than enough for video and it is much more useful to invest in more capacity rather than speed. I hope that helps :)

  3. Matthew says

    I actually own a 7D and just got off customer support about this. I use a 133x card for video with the 7D and recently it has been turning off prematurely due to the buffer rate being exceeded. The rep told me I needed a faster card, even a UDMA card to ensure the video would go through without issue. I’ve used 15 MB/sec cards without issue before but if you crank up the ISO or really push the video limits the card won’t be able to take it. My next purchase will be a card that runs at least 40 MB/sec to ensure I don’t have to stop shooting. Hope that helps.

  4. says

    Thanks Matthew,
    What settings did you use to push the limits? I’d be curious to try them out.
    I still haven’t experienced any issues with my x133 card and, as a matter of fact, just ordered a second one.
    Also, quality among manufacturers, not to mention fake cards (rated higher than their capabilities) also come into play. What brand have you been using and did you purchase it from a trustworthy source?

  5. Matthew says

    I got a 16GB CF card from Kingston that runs at 133x. The conditions that caused the buffer speed to be an issue have been when I’ve been in either very bright conditions or very dark conditions. I did a shoot outside at night with a single spot light and I was limited to about 30 seconds of shooting before the buffer was exceeded. The other time it happened was when I was recording a fox walking on an iced over pond. The reflecting ice was pretty bright and I’m guessing that’s what got it. I don’t recall what settings I was using for either case but it’s happened since then as well. I’m probably going to go up to a UDMA card just to be safe next time. Next time it happens I’ll take note of the settings I’m using and let you know the details though.

  6. says

    Slower cards will limit the length of each video clip you can product. The camera shoots directly into its internal buffer and from there the data is moved to the card. When the buffer is full, the video stops. Therefore, the faster the buffer is empties, the longer clip you can shoot. The real question is how fast does a card need to be to allow you to fill it up with a single video clip. I don’t know the answer, but clearly it is dependent upon how large the card is.

  7. peter says

    So would a Sandisk Extreme III 4GB CF be enough for video shooting and raw/jpg stills???

    I’m thinking of buying 4 or 5 of these then rather have 2 16GB. Because of the costs and the fact that if 1 of my 16GB breaks down I only have 1 left. And if 1 of the 4GB breaks i still have 3-4 left.

  8. Matthew says

    I’ve got an extreme III now and it works great. I’ve never hit the buffer. I’d go with that for video.

  9. peter says

    Sorry forgot to mention that the Sandisk Extreme III 4GB CF i meant is a 30mb/s. Just for info. Is this still enough for 1080 video and raw/jpg stills???

  10. says

    Peter, 30MB/sec is plenty enough… Canon recommends 8MB/sec, so you should double that just to be fine (16MB/sec). And you have 30MB/sec which is almost the double again… You shouldn’t have any problem here

  11. tj. says

    I have the 7D and have been using a 8GB SanDisk Ultra 30MB/s without any problems. I shot basketball indoors for up to about 4 minutes at a time without any problems [stop shoot during dead ball timeouts]….except I filled the card up before the game was over. I agree with Jan…get more capacity…16MB or 32MB card for sure.

  12. jacopopasotti says

    Ok, after reading this I think I will get me a SANDISK CompactFlash Card Ultra II, 16GB. I am not interested in video and stills together, but HD videos, with reasonable time of recording, as I will do some short interviews (some 4-5 minutes). Do you think it will do?

  13. says

    From the descriptions I can gather relative to this card it is rated for 30MB/sec (200x). So yes that will do it just fine. One thing I would double-check though is that on all product pictures I saw the rating has a little asterisk next to it (like this 30MB/s 200X*) meaning there must be some fine print. Just make sure the card can properly sustain its advertised speed.

  14. Patrick says

    My Canon 7D has problems with 133x card when there is a lot of motion (like a street traffic). I recommend getting at least x200 card.

  15. says

    I have 7 D and 8 GB Silicon Power 133x CF card, I only cand shot 640×480, but when I shot 1980 x1080 and 1280×720 buffer fills up and stop the movie. So get a real UDM card and 32 GB minimum for shoting muvie :)

  16. Neil B says

    I have had a 7D for a year and have also had problems with buffering on slower cards. I eventually bought a 8gb Duracell UDMA card for £19.99 from, and since then no problems at all.

  17. Michel Merx says

    Thanx for the advice’s!

    Have a good day!
    -Michel Merx.

    p.s. I’ve found out that 133x and 200x umda -CF’s are sold at the same price on ebay

  18. Matt LoGuercio says

    I bought a 32 gb 133x kingston elite pro (yeah right). Anyone want it? so slow it cannot even take pictures. cannot shoot video.

    there is a reason why the faster ones cost so much. Run from this Compact flash!

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