Sandisk Memory Cards

[Dr Croubie]

Thought I'd throw my own results in here, even though I've only got 2 cards the same speed and one 7D body.

70-300L, 70mm, f/5.6, iso100, 1/125s, pointed at a white wall. TC-80N3 set to 20s-long 'bulb', but camera set to HSC. Fully charged battery, cards formatted in-camera. Firmware 1.2.3.
ALO off, PIC off, all noise reductions off. I didn't time the length of the "busy" light or the red "write"-light afterwards

8GB Sandisk Extreme 60MB/s card, RAW-only: 68 frames, 1.2GB (1,304,866,608 bytes).
16GB Sandisk Extreme 60MB/s card, RAW-only: 69 frames, 1.2GB (1,324,110,624 bytes).
a) that's a good result, because I bought my 16GB card in hong kong for the same price as the 8 in Holland (ie, it's genuine or at least a good-speed ripoff).
b) Not sure why the 8GB missed its last frame, maybe because I forgot to format it but did format the 16GB?
c) viewfinder says 16 images possible, but I get 22 before the slowdown to bursts-of-2 roughly every second.
d) 18MB per .CR2 file.

8GB card, RAW+LJPG: 56 frames, 1,240,964,468 bytes.
16GB card, RAW+LJPG: 57 frames, 1,262,978,180 bytes.
a) again the 16GB gets one more frame in (both formatted in-camera pre-test this time).
b) viewfinder says 6 possible shots, but I get 8 before the slowdown.
c) I always thought that the jpg-processing overhead wasn't much, seems I lose ~60MB over a 20 second burst, ~3MB/s slower.
d) 18MB CR2, 3MB JPG or so.

8GB card, LJPG-only: 153 frames, 435,550,489 bytes.
16GB card, LJPG-only: 153 frames, 429,442,384 bytes.
a) size difference was about 2 JPGs-worth, but same amount of frames.
b) Viewfinder said 96 shots available, but absolutely no slowdown in 20 seconds. Should i add more to my shutter-count to see how many JPGs I can get before a slowdown?
c) 2.7MB per JPG or so.

For the hell of it, I found an old 512MB "Pretec 80x" card that i've been using as an IDE drive in a firewall (built from an old pentium 1 using ipcop) for a few years and recently upgraded.
RAW: 20 frames or so, then 2 second wait, frame, 2 seconds, frame, 5 seconds, frame, then Full CF (maybe missed out on one frame in the end). 25 frames, 476,331,819 bytes.
RAW+JPG: still get 8 frames before the slowdown, then a few bursts of 1 or 2, a 5-second wait, 1 shot, a 5 second wait, then the 20-seconds is up. The "writing" led doesn't go out for about a minute or two afterwards, I thought I'd broken my camera. 20 frames in total, 440,834,628 bytes.
JPG: 13-seconds before a slowdown, then a few bursts of 1 or 2 frames each. 113 frames, 315,670,763 bytes.

The results for the crap-card are interesting in that you get an idea of the performance of the buffer. ie, I still got nearly the same number of frames before the slowdown in all but LJPG, but once the slowdown started, the camera's nearly unusable for 2 minutes.

[Kayaker72]

Dr. Croubie....I like your results and I think they highlight one of the things I've learned doing the testing. I think the burst number of shots shown in the viewfinder only reflects the images that can be written to the buffer but does not account for images being cleared from the buffer during shooting. In otherwords, the number of shots you can take until the buffer is full is the buffer size/image size + write rate * time/image size, or, for the 7D, the 15 Images the viewfinder says plus the extra 7-8 images that can be written in 3 seconds of shooting (with a fast enough card) equals the 22-24 burst images we've seen in our test results.

Speaking of the test results, I wanted to summarize those that were conducted using the same methodology and I assume John/Neuro will repost his table....



Rick and Rich, please let me know if you would like me to modify in any way....

Thanks,
Brant

[Kayaker72]

Looks like CF card prices are back up...almost double what they were.