One of the advantages of digital photography is that the medium itself is very stable. Take your CF or xD card and bake it in Death Valley, freeze it in Siberia, and run it through the high power X-Ray machine at the airport of your choice as often as you like. Drop it; step on it; cover it in dust. Take it out of the camera any time you feel like it; it really dosn't matter. With operating temperatures that generally range from around -5°C to 60°C, storage temperatures that can range from -20°C to nearly 100°C, and shock ratings over 1000g, today's digital media are sturdy and versatile. Nevertheless, most of us probably lose more digital pics in a year than we've lost rolls or cartridges in our lives, because although they are physically sturdy, digital media are extremely susceptible to human error. If you're anything like me, you routinely trash at least one cardfull of pics on every vaction because, while navigating buttons designed for extremely dextrous pixies, you hit 'delete all' instead of delete, or don't protect the pictures you meant to protect, or can't quite make out the LCD in the sunlight.

Fortunately for all of us, there are ways to get back lost images, but they work best if you are proactive about preparing for data loss and recovery. I've put together a list of some of the most important techniques. Feel free to add some of your own strategies.

1. Carry extra cards. You need to stop using a card as soon as you realize there’s a problem. Otherwise, you risk recording a new picture over the one you’ve lost, making it unrecoverable.

2. Use different cards for different formats. Recovery programs work by looking for a unique string of bytes (the Start of Image or Image File Header) that identifies file type. If all the files on a card are JPEGs, it’s relatively easy to figure out what’s what. But there is nothing to prevent a RAW or TIFF IFH from appearing in the middle of a JPEG, or vice versa, which can make your recovery program think that the file is ending and a new, different file is beginning, and leave you with two garbage files instead of one recovered picture. Use one card for JPEG, one for RAW, and another for TIFF if at all possible.

3. Erase your cards regularly. Start each shoot with a fresh card, if possible. Almost all cards are formatted FAT-16 (some large ones are FAT-32). This means that, as much as possible, your pictures will be assigned contiguous disk space, and blocks on disk will be filled sequentially. The first picture you take will start at the first data block (more or less; the camera keeps some administrative information on disk), and your second picture will start immediately after. This makes it very east to find SOI markers, and also easy to quickly evaluate the esults and see what was recovered, and what wasn’t. When you erase pictures, though, as the disk fills up the camera will try to save new pictures in the ‘holes’ left by the shots you’ve erased. Where the pictures don’t fit cleanly into that space, leftover data from the deleted file can be appended to a recovered file, corrputing it, or the file can be fragmented and part of the data lost, like the pic at the top of this post.

4. Make a copy of your card before attempting recovery. Some recovery programs may try to recover the images in place. Something might also happen to disconnect the usb or firewire connection while you are in the middle of recovery, further corrupting the data on the disk. Whatever the possibilities, mount your card—read only if possible—make a byte copy or image using a “raw” copy tool, and recover from the image. That way, if something goes wrong with the recovery, you can always try again.