I read that CF cards can be rewritten for at least 100,000 cycles. I am an amateur but seem to do frequent deletes due to bracketing, continuous shooting, etc. I also read that if you keep a card in the computer, the computer continually accesses the card, each access being equivalent to a write cycle.
Just wondering if others could share their experience on how long their cards (mine are Sandisk Extreme III) last under various kinds of use.
I use a 20D/40D and would also like to hear statistics on how many shutter counts they are good for in real use. Thanks.
KPBara wrote:
I also read that if you keep a card in the computer, the computer continually accesses the card, each access being equivalent to a write cycle.
That is odd. What writing are you seeing in the logs?
dont sandisk have a lifetime warranty? so if it crapped out before you were prepared to just through it away (ie to small/slow in the future) it would be replaced
Murphy's Law, the "Fickle Finger of Fate" or just plain losing the card are far more likely than ever wearing them out. In fact, I can pretty much guarantee you will replace it with a bigger/faster card long before you wear it out.
Never have I seen anyone write about a card giving the message that it is worn out.
I rounded these numbers off a bit, but lets say you can fit 300 RAW images from your 40D on a 4 GB card. Due to wear leveling done in the CF card, which randomizes where the data is written in memory to avoid the sectors at the beginning of the card wearing out first, I believe you'd have to write about 300 * 100,000 = 30,000,000 raw files to wear out your card.
alanwarp, I am not sure I follow your argument. Please correct me if I am wrong but I take one cycle to mean each time you delete and rewrite images, and not necessarily the entire card's content.
Regarding card in computer, I sometimes use DPP to make changes directly to images on the card. The article I read says that under this circumstance, the computer accesses the card continuously and each time is equivalent to a write cycle.
KPBara wrote:
alanwarp, I am not sure I follow your argument. Please correct me if I am wrong but I take one cycle to mean each time you delete and rewrite images, and not necessarily the entire card's content.
You only write a small percentage of the cards memory with each picture taken. If that picture went to the same location in the card's memory every time you took it, the card would start wearing out around 100,000 pictures.
But that's not what happens, every time you take a picture it goes to a different location in card's memory due to wear-leveling built into the card. So the memory wears out evenly, it's like the card is rotating its tires.
Each block of memory can take 100,000 writes, but you only write a fraction of the blocks with each picture.
BTW, do you have a link to this article you keep referencing?
KPBara,
Note that the article is talking about a half million write cycles not read. Also note that this number is a statistical estimate not an average based upon real experience. Also note that unlike hard drives and floppy drives nothing physical ever touches the CF card media. It is read and written with light. Also, when a card is read it only reads the VTOC (volume table of contents) and the appropriate places on the card. Finally look at alanwarp's rough numbers again. Even if he is off by an order of magnitude (he isn't), 30 million accesses is rather inconceivable. If you are losing sleep over this do the following: only put the card into the reader to dump image files to DPP or whatever you use; eject and format in camera; and set up a regular replacement card replacement system. You are far more likely to lose, step on, magnetize, leave in the sun, or just get plain tired of how small/old the card is than wear it out.
