CF card for 7D

BGtom

Hey all,

Starting to feather my nest for my "pre-ordered" :bow7D...and am trying not to dip into the food budget for next month paying for spendy new CF cards.

I calculate that @ 8fps :ivar i will need a card that can write ~48MB/s (HQ jpegs). Then it occurred to me that it's actually writing to the buffer first before writing to the card. I see from the 7D preview on dpreview.com that it will shoot 126 jpegs continuous before filling the buffer. That seems like a lot...especially since the specs call for 15 RAW before filling the buffer. Those two numbers don't seem to add up.

I'm staring at my 2GB SanDisk Ultra II's that transfer @ 9MB/s and wondering if I don't really need to spend $130 for a SanDisk Exreme that writes @ 60MB/s. I know that I will be twiddling my thumbs once the buffer is full (would that really be more than a minute?!), but I don't anticipate shooting 126 frames continuously for anything. During a football game I usually fire off 5 sec's worth of shutter release per play. What do you 1DMIII guys use?

Thanks!

Scott_Quier

Having just shot a gig with a 5DII using the Sandisk Ultra II cards (and shooting RAW), I can tell you that waiting for the buffer to clear is a pain in the back-side. I lost a couple of shots because I've been in the habit of removing the full card shortly after I finish shooting and ended up corrupting a couple of images - oh well. However, I've not yet had a problem (speed wise) with the 300X Transcend cards (I have 4 4GB cards) and I'm seriously contemplating moving up to these Transcend 16GB Compact Flash (CF) Flash Card Model TS16GCF300 in the very near future because the 4GB cards are a bit more than a touch too small.

ziggy53

With 2 image processors the 7D can process images almost as quickly as they are shot. JPGs are 8 bit, but the RAW files are 14 bit, stored as 16 bit. That's part of the reason for the disparity in buffer storage quantities. The other part is that JPG files are intrinsically lossy in the method of compression. The RAW files are intrinsically lossless, making them much larger.

I have shot sports with the Canon 1D MKII and I did use JPG format since I was mostly interested in maximizing the buffer storage and writeout speed (to the storage card.) As long as you are very careful about exposure and you don't get stuck with lights that flicker too much, JPGs can work pretty well for sports.

I suggest you try a game with your existing cards, but add at least one more card and make it at least a 4 GB UDMA card. Compare your results afterward to guide you in future purchases.

Sandisk are generally very good cards, although we have had 2 members with problems recently, and the later version of the Extreme III CF cards are UDMA, as are all of the Extreme IV CF cards. I do think that UDMA would give you a considerable boost in speed and the Extreme III, 4GB CF are not too bad in price.

AlbertZeroK

Transcend has some nice new 600x cards out. I shoot with the 300x and the 600x. The 600x is awsome, but the 300x is still the bomb. If you are into the rebate thing, you can get 3 8G Sandisk Extreme IV cards for $300 with a $200 MIR at adorama.com - just be careful, you may have to RMA them when you get them as their is apparently a bad batch out there.

I bought my Transcend cards at Newegg.com - 8G 600x cards were $100, 8G 300x cards were $75 or there abouts.

Oh, I have the 16G transcend cards Scott recomended. Very nice.

craig_d

When I got my 5D2 recently, I looked around for UDMA CF cards. The top of the line seems to be the Lexar 300x cards, but they're really expensive. I ended up buying two Kingston Ultimate 266x 16 GB cards for, if I recall correctly, a little more than the price of one Lexar 300x. Performance has been very good; the camera responds quickly, and pictures transfer from the card to my computer at a rate of about one picture per second using my Lexar Professional UDMA USB CF/SDHC reader.

BGtom

Do the write thang...
Thanks for the info. Oi! these marketing geniuses! They do loves their "x's." Imagine my shock to find the root speed of UDMA is 153 kilobytes/s! Did they even make anything with that speed?

It sounds like 9MB/s (66x) will keep me sitting there for days. 300x (45MB/s) seems like the way to go. Can't afford 600x. I could buy a new lens for that!

Thanks for the help everyone.

ziggy53

BGtom wrote:

Thanks for the info. Oi! these marketing geniuses! They do loves their "x's." Imagine my shock to find the root speed of UDMA is 153 kilobytes/s! Did they even make anything with that speed?

It sounds like 9MB/s (66x) will keep me sitting there for days. 300x (45MB/s) seems like the way to go. Can't afford 600x. I could buy a new lens for that!

Thanks for the help everyone.

Unfortunately, the manufacturer rated transfer speed doesn't mean too much because there is no industry standard for testing.

The best way to know true transfer speeds in a combination camera and flash memory card is to test empirically, and the only site that tests card-camera combinations is the site at Rob Galbraith. Until the 7D has been tested, transfer speeds are only guessed at.

Review some of the other Canon cameras tested with memory cards to gain some insight:

50D transfer speeds:
http://www.robgalbraith.com/bins/camera_multi_page.asp?cid=6007-9672

5D MKII transfer speeds:
http://www.robgalbraith.com/bins/camera_multi_page.asp?cid=6007-9784

BGtom

corporations are on

ziggy53 wrote:

Unfortunately, the manufacturer rated transfer speed doesn't mean too much because there is no industry standard for testing.

No industry standards?!?!? Why am I not surprised. Thank you for the links. I has sum learnin' to do.

rookieshooter

Don't believe the numbers. If it's anything like my D700 at 8fps, the max burst before it has to transfer from buffer to card and wait a bit is about 10 frames. I shot video of it comparing UDMA to fast CF if you are interested and posted it in the camera forum.

link: http://www.dgrin.com/showthread.php?t=143609

Village Idiot

Just make sure you buy through a site you know is legit. Amazon has retailers selling fake CF cards via their site. If it's too good to be true, you know the rest...

Cuong

Even speedier CFs are being introduced for those who really need and can afford them:
http://www.robgalbraith.com/bins/content_page.asp?cid=7-10043-10255

Cuong

BGtom

new CF cards
Just got my new 32Gb SanDisk Extreme cards with a claimed write speed of 60MB/s. I haven't gotten my 7D yet to try them with (Amazon says should arrive tomorrow...) but i did try them in my xti to see if there was any difference. My 2GB SanDisk Ultra II's would clear the xti buffer of 10 RAW in a very un-scientific 17 to 20 seconds. The Extremes' would clear it in about 13 to 16 seconds. From a test of the ultra II's on Rob Galbraiths site on the 40D, they reported about 8.5MB/s. So the Extreme's help only about 25%, or about 11MB/s, in line with the best cards at the top of the chart, but not worth the money for this camera.

Of course I didn't buy the Extremes for the xti, I got them for the 7D. So here's hoping the UDMA transfer will keep my buffer as clear as my sinuses.

By the way, I noticed files sizes increase with ISO...I also noticed that images with a lot of white/overexposed images are larger than dark/underexposed images. Anyone know why?

ziggy53

BGtom wrote:

... By the way, I noticed files sizes increase with ISO...I also noticed that images with a lot of white/overexposed images are larger than dark/underexposed images. Anyone know why?

Image compression schemes cannot distinguish between image detail and noise. More random noise is treated the same as more image detail, and it allows less compression.

Likewise dark regions probably lack appreciable detail. Most image data is contained in the highest 3 stops of dynamic range. It should be possible to create images of very high key that also compress to smaller files however.

wildviper

I guess a question about these higher capacity cards...16gigs, 32 gigs and so on.

Are you guys/gals not concerned about card crashes? If the card fails, a LOT of the pictures could be gone, no?

AlbertZeroK

wildviper wrote:

I guess a question about these higher capacity cards...16gigs, 32 gigs and so on.

Are you guys/gals not concerned about card crashes? If the card fails, a LOT of the pictures could be gone, no?

I have a 32G card for time laps work. I typically use an 8G card, but have some 16G Cards. When you shoot RAW+JPG, the extra room comes in handy, especially with a 50d, which is a 16 Megapixel camera.

insanefred

Just look for UDMA cards, generally it'll be good enough. I use Lexar pro 300x UDMA and Trancends.
Luxer works great, trencends has a little slower read speeds.

insanefred

wildviper wrote:

I guess a question about these higher capacity cards...16gigs, 32 gigs and so on.

Are you guys/gals not concerned about card crashes? If the card fails, a LOT of the pictures could be gone, no?

AS long as you stick who brand names from authorized dealers, I am confidant you'll be ok.


For me bigger cards are always good, less time fumbling/swapping cards in the rain, snow, and other environmental hazards.