When I talk to digital photographers about the nuts and bolts of the craft, there’s a topic that comes up unusually often: what size flash cards to use in your camera. There are photographers that say that you want to keep the card size small, so when there’s a file system error, you won’t lose as much work. There are photographers who opt for convenience, and use cards that will hold pretty much a whole day’s work. There are photographers who haven’t thought much about it, and by the end of most discussions with the other groups, they’ve gone from blissfully unconcerned to mildly paranoid.
I think this is one of those things that has suffered from way too much analysis. With decent quality memory cards, it’s extremely unlikely that there with be file system corruption while the card is just sitting in the camera, or, for that matter, while the card is tucked into a pouch in your camera bag. I base this opinion on the fact that the file systems used for flash cards in cameras are the same file systems used on many (admittedly, older and smaller) hard disks. We know that the flash memory is itself reliable in permanently connected applications like fast hard disk replacements in portable computers. Problems will occur, if they occur at all, while cards are being inserted or removed from the camera or the card reader attached to your computer.
If you buy that, then the probability of file system corruption on a memory card is inversely proportional to its capacity, assuming it’s usually almost filled before it’s pulled from the camera. The number of pictures lost per incident (assuming that file system corruption typically wipes out all the files, an extremely pessimistic assumption) is directly proportional to the size of the card. The size of the card in the numerator cancels the size in the denominator, and the number of pictures lost is the independent of the size of the card. If you accept the proposition that most file corruption problems cause partial data loss, then you’re better off with larger cards.
That said, I’m not sure the subject is worth much attention, let alone mild obsession. In ten years of flash-card digital photography (leaving out the really old days of spinning disk photography), with well over 250,000 exposures, I’ve yet to lose my first image file. Maybe I’m am outlier, but I suspect that file system corruption in the real word is caused by:
- Removing the card while the camera is writing data to it.
- Using off-brand flash cards (there’s a reason why they’re half the price of the good ones).
- Removing the card while the computer is writing to it, and then failing to reformat when the card is reinstalled in the camera.
Moving to a larger issue, I’ve asked myself why technical concerns of one sort or another seem to loom large in digital photography. I think many digital photographers have a general discomfort and distrust of the underlying processes with which they’ve chosen to work. They know that people have lost valuable images to digital gremlins. Maybe they’ve even lost some of their own work. They don’t know quite how it happened, but they want to keep it from happening again.
Combine that generalized fear with the Internet’s amazing ability to spread opinion without a process to test that opinion. Voila! Magical thinking.
Maybe I’m way off base here. Maybe I’m too comfortable with digital technology — Lord knows, I feel a lot more at home with it than with the details of the chemical reactions that underlie wet photography. Maybe there are mysterious forces at work in my computer. I accept that there are weird things that happen in my desktop — I call those things bugs — but the idea that the main cause of data loss is random, and beyond the control of the photographer, and thus that the best we can do is damage control? That’s hard for me to get my head around.
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