Think of memory cards as the film for digital cameras. Cards are where your images are stored.
At The Dallas Morning News, we've bought hundreds and hundreds of cards in the past few years and have learned what works well - and what doesn't.
Let's focus on CompactFlash cards and what to look for when buying them.
While CompactFlash cards are the most common type of digital medium, some digital cameras take other media, such as Memory Stick and Smart- Media. Most of what follows will apply to these types of cards as well.
CompactFlash cards are solid-state storage cards. They have no moving parts and come in a variety of sizes (from a tiny 8 megabytes to a huge 4 gigabytes), and a variety of speeds.
Unharmed by X-rays
Solid-state CompactFlash cards are tough and generally reliable if treated well. We've even had a couple that went through the wash after being left in a photographer's pocket, and they still work.
They safely travel through airport screening with no ill effects. According to the CompactFlash Association, the carry-on or checked baggage X-ray systems at airports will not damage solid-state CF cards.
At the newspaper, we have hundreds of CF cards that have been in use for several years by our photographers, and we have never encountered a problem with airport X-ray systems around the world.
Anyone who has purchased a digital camera in the past few years probably quickly realized that the 8MB or 16MB card that came with it was way too small for extended shooting.
To determine how large a card you need, consider how many megapixels your camera has and how many images you want to capture without changing cards.
For most 3- to 5-megapixel cameras on the market, a 256MB to 512MB card provides plenty of storage for the average user. This is also the sweet spot in terms of price per megabyte as well.
The other important factor to look at in CompactFlash cards is write speed - that is, how fast your camera can write the images to the CF card and how fast you can download those images off the card onto your computer.
Almost always, a faster-rated card is better. Your camera will spend less time writing images and more time taking them.
An excellent resource for comparing write speeds of CF cards in different cameras is digital guru Rob Galbraith's Web site, www.robgalbraith.com.
Prices are dropping
Many CompactFlash cards are on the market. As with most electronics, prices have dropped drastically in the past year or so.
With professional-rated 256MB cards under $100 and 512MB cards well under $200, buy the fastest cards available in the size you need.
Also, check the warranty carefully. We've had good luck with Lexar and MicroTech cards over the years - a low failure rate, even with the abuse our photographers can dish out. Other major brands should be equally reliable.
Occasionally, CF cards won't mount on your computer or your camera won't display images that were there just a minute before. Often, images can be recovered from cards that appear to be corrupt.
A program that we have used with great success is PhotoRescue ($29 for Mac OS X or Windows; see www.datarescue.com). If the CF card is not physically damaged, PhotoRescue frequently can recover images that appear to be lost.
Another program that we have used with success is Lexar Image Rescue, which works in a similar manner. Lexar Image Rescue ($40; www.digitalfilm.com) performs only with Lexar CF cards, but it is included free with Lexar's professional-level cards, along with a free USB card reader.
In my experience, most image corruption problems have been caused by shooting a card until it is full. Stop using a card when it is about 90 percent full and switch to another card. These images can almost always be recovered.