Photography 101: Memory Cards for Digital Cameras

What is a Memory Card?

A memory card is a storage device commonly used by digital cameras to write digital photos. It is a mechanism to store your photos, and later transfer them to computer for processing and printing. Essentially, a memory card is to a digital camera what a hard drive is to a computer. That means that the size of your memory card directly affects how many images you can store, and the speed of your memory card directly affects the how fast your camera can read and write photos!

The Need for Speed

As digital cameras evolve to store higher quality images, image size increases, and it becomes more important to find a memory card that is fast enough to write these images before you want to take another shot. Compact Flash (CF) and Secure Digital (SD) formats are two types of memory cards that are improving their speeds dramatically to keep up with high megapixel counts in newer cameras. Not only does a faster memory card allow you to take a second shot sooner, but it also results in quicker download to your computer. The larger your memory card’s storage limit, the more important transfer speed becomes. Otherwise, a 2 GB memory card might require an hour of transfer time!

Memory card speeds are measured based on a standard where 1x equals the transfer of 150 KB per second. That means that a 10x memory card transfers data at a rate of 1.5 MB per second and a 133x memory card transfers data at a rate of almost 20 MB per second. These numbers usually indicate the best possible rate when the card is used with a camera that has a super fast recording capability. Certainly not every digital camera is coded in such a way as to take advantage of these peak transfer rates, so you may wish to research very fast cards before purchasing. For example, Lexar has a line of 133x memory cards, but the super fast rates required cameras to be designed specifically with their card’s technology in mind – in this case, they provided a list of cameras that would result in fast rates, but my camera wasn’t on the list.

There are two types of speeds you should be aware of, each of which is measured relative to 1x:

1) Write speed – the time it takes your camera to save an image to the memory card
2) Read speed – the time it takes your camera to open an image on the memory card

Care of Memory Cards

Here are some TIPS from the professionals on how to keep your memory card functioning correctly for years to come:

1) Reformat your memory cards periodically to remove residue files system information and help optimize data access and storage. Try formatting after you transfer your files, or before a major shoot. Remember, when you reformat your memory card, you will lose all images stored on it, so be sure your transferred copies are good.

2) Never remove a memory card from your camera or card reader until the processing is complete – there should be a blinking light to indicate that transfer is in progress. Cards can be damaged if you remove it during image transfer.

3) Replace or recharge batteries when the low battery light comes on so that your camera does not run out of power while writing your last shot to the memory card. You could corrupt an image or your card during an important or memorable trip otherwise.

4) Never expose your memory card to excessive heat or moisture.

Upgrading your Memory Card Firmware

The firmware on your memory card is its operating system (OS), and occasionally needs to be updated. Your memory card’s manufacturer will most likely make an update available for download from the internet, directly to your camera or card reader.

But before you upgrade, be aware that the latest version of the firmware may affect the promise of speed. One article I read suggested that the Lexar 133x WA CF card had better performance after a firmware upgrade, although that only coincided with a firmware upgrade on the camera it was being tested against. So it may be worth your while to compare your current firmware version against the latest offered by your manufacturer and see if the changes in functionality or performance are important to you. Be sure you look for disclaimers or notes about side-effects. You will not likely be notified in person when memory card firmware upgrades are made available to consumers.