Originally posted by Peter Zack Always reformat in the camera After the data has been securely downloaded. Even the best cards can cause issues.
I must respectfully disagree. Since 2002 I've used various digital cameras by Pentax, Minolta, Olympus, and Sony, using variously MemSticks (Sony), XD cards (Oly), and a few breeds of SD. Of the couple dozen or so cards I've bought, I have had NO [zero none zilch] corruption problems. when offloading via USB cable or a SanDisk multicard reader, or card readers (SD and MemStick) embedded in computers. I *did* have a problem with a no-name multicard reader, which insisted on reformatting cards after offloading. And I had a problem with an SD card formatted in a Minolta PNS which the Pentax K20D couldn't read -- reformatting on the K20D left the card still usable by the Minolta. Go figure.
I don't reformat after each offload because I have common directory structures on each card, and a common script (kept synchronized with my various net'd laptops). I carry different laptops on different journeys, and plug in various USB etc stuff that looks like different virtual drives. With the common structures and script, each card knows precisely how to rename files to identify the source camera, and where to offload on each computer, because the script is run from the card, not from the laptop. With the MemStick (Sony) cams, and the SD-card (Minolta & Pentax) cams, I can swap cards as needed, and images from the current camera always end up in a known directory with proper names. Reformatting after offloading would destroy all this and make managing my photos much more difficult.
I should also note that when I buy a new card, I stress-test it by loading and offloading, moving the card between cameras and computers, all repeated a few times. No cards have failed to pass the stress test, and none have suffered problems (yet). I'm a retired software engineer (burnt-out codemonkey); I treat memory card usage as just another form of system integration. Test them with paranoia, watch them carefully. If anyone else wants to perform continuous reformats, fine, but that's not for me.