Format CompactFlash?

Started Feb 14, 2008 | Discussions thread
dopravopat Senior Member • Posts: 1,178
Re: Format CompactFlash?

I use a Canon EOS 30D and regular Sandisk 4 GB CF card (no Ultra). Here is how I format the card in a card reader:

format x: A:32k

where x: is the drive of the card

format_cf.dat should be, as seen above, located in the C Root, and should be like this (for EOS cameras):


With a 8GB card you can try the cluster size of 64k, it should work, athough I never tested it. Try always to have the biggest cluster size possible.

Why? To undersand it simple: There is a little man inside the camera and he is moving data between the card and camera with a shovel. The cluster size of the CF card defines the size of his shovel. So the bigger the shovel, the faster he can move large amounts of data. The speed incerase is not very high, but still noticeable. By incerasing the cluster size the cards useable capacity gets a little smaller, but there is no big difference, especially when using 4 or 8 GB cards it is only a few images, compared to how much would fit on the card when formated to the standard, small cluster. I belive it is worth the extra speed. I really do not mind if I can store 400 or 495 RAW files. No big deal.

My cheapo Sandisk 4.0 GB CF card is faster, compared to in-camera formating. When I reformat it in the 30D, it is slow again. But deleting images does not affect the cluster size. The most important difference is when I download images from the camera to PC. I never use a card reader. The card is downloaded faster from the camera when it is formatted like this. Also, the read/write process in-camera are faster, but I value the fast download from camera more. I never format the card in the 30D, only do a full delete.

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Canon EOS 30D Canon EOS 60D Canon EF-S 18-135mm F3.5-5.6 IS Sigma 8-16mm F4.5-5.6 DC HSM Sigma 17-50mm F2.8 EX DC OS HSM +8 more
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