One of the most memorable afternoons I spent when I lived in St. John's Newfoundland, was a trip to see the humpback whales off the island's Southern Shore. In late spring, they arrive from their winter breeding grounds in the Caribbean in enough numbers that a short boat journey almost guarantees a sighting of these grand creatures, which can grow up to 15.2 m (50 ft.) long and weigh up to 41 tonnes. Happily, my memory is good because the local photofinisher was not: the two rolls of film I shot were destroyed when the machine jammed and the technician opened it, exposing my shots of humpbacks breaking the ocean's surface to the cold light of day.

For those of us without a darkroom, film photography has always included an element of chance. The odds are highly in our favour, but light, unskilled technicians, or badly maintained developing equipment can be the equivalent of rolling snake eyes.

Digital photographers at all levels no longer have to take this gamble: they control their images from capture to print. Even if a photofinisher is entrusted with the printing, the photographer hands over a digital copy, not the original, which is kept safe on the media card or--even better--backed up on a PC hard disk or CD. Despite the reduced risks, digital photography's "film" equivalent has its own vulnerabilities.

Blame it on the rays?
One of our readers, Barclay Craig, recently returned from a tour of the Dalmation Coast, where he says he nearly filled two 256 MB and one 64 MB CompactFlash cards with photos. On slipping one of the larger capacity cards into a card reader on his return, it would only display 157 MB of images--the last 28 images were missing. He wrote, "Checking with SanDisk tech, I was told that the loss was probably caused by the x-ray machine at the airport security check-in. This had created a fault in the formatting of the card."

There is very little information available on this matter, and what is there is conflicting. SanDisk's FAQ lists airport x-rays as a factor, but flash card maker, Crucial, states emphatically that "flash memory cards are not affected by the new, high-security, x-ray machines used in airports today."

So, next time you fly with your digital camera, you may want to do as Mr. Craig has decided to do, and carry your media cards separately for hand inspection.

Proper care and feeding of flash memory
Even if they are never exposed to x-rays, there are a few precautions you can take with your digital camera's memory cards. The memory recovery specialists at FlashFixers (www.flashfixers.com) offer the following tips:

• Reformat cards in your camera after downloading and saving pictures on your computer. Don't use the computer to format the card.
• Backup files from the memory card to your computer. You might also want to create a CD backup.
• Don't let the memory card get too full before downloading the pictures to your camera.
• Make sure batteries are charged sufficiently.
• Don't remove the card while camera is saving data to it.
• Wait a few seconds for the picture to write to the memory card before shutting camera off.
• Don't exceed manufacturer's recommendation for taking pictures one after another. If taken too quickly together, the camera will not finish writing one picture completely before starting the next.
• Avoid large static charges, and be extra careful when handling cards in dry, low-humidity areas.
• Keep cards away from strong magnetic sources and extreme heat and cold.
• Don't remove card from card reader until it has finished communicating with the hard drive and all files on that card are closed.
• Some PC recovery applications, like Norton, Scandisk, and Fdisk, actually write to the card and can make corrupted cards worse. Don't use them for photo recovery.
• On a Mac, remember to trash the icon first before removing the card.