Learn the Terms > Memory Cards

Memory Cards

The film for a digital camera

CompactFlash. Memory Stick. xD Picture Card. MultiMediaCard. Secure Digital Card. SmartMedia Card. There is no lack of variety in the removable media market for digital cameras. These are the tiny devices that will store all of your precious photographs.

Once again, there is no end to the information about the benefits of each one. Faster, smaller, cheaper, more standard. Every manufacturer will tell you that their storage is the best. Coincidentally, two of these storage cards are the proprietary technology of specific companies.

Are there substantial differences?

All of these memory cards work pretty much the same. They store digital photographs so that you can later transfer the photos to your home computer. If you're taking professional photos with a fast camera, you may be able to tell that one is faster than the other.

Here's something that will help make your decision easier: the camera that you decide to buy pretty much determines the memory cards that you will use. Focus on the features of the camera you want, and worry about its memory cards later.

From shutter to storage — how a digital photograph is taken

You press a button and the shutter opens and lets in light (based upon your aperture and shutter speed settings). The light is captured by the image sensor (CCD or CMOS) and is then processed into a digital photograph.

All well and good. The camera has created a digital photo. Now what? It has to save the photo to some location so that you can take the next photograph. While a few cameras have internal memory to store photos, the large majority of digital cameras save photographs onto removable memory cards.

CompactFlash cards are the most common, and can be used with a wide variety of digital cameras. xD Picture Cards are exclusively used with Olympus digital cameras, since the cards are developed by Olympus. The same is true of the Sony Corporation and Memory Sticks (although Sony has just released a camera that also uses MicroDrives).

Memory card capacity

When you purchase film for you camera, you can get a roll with either 24 or 36 exposures. The same concept can be applied to removable memory cards, although the differences are somewhat more drastic.

Despite the wide variety of types of removable media, they all come in pretty much the same capacities. Card capacity is measured in MegaBytes, just like files that are stored on your computer. The higher the number of MegaBytes, the more photographs the card can store.

The following table shows the number of photos that can be stored on the different types of cards, assuming that the camera is 3.0 megapixels. These numbers will be higher for a camera with less megapixels and lower for a camera with more. More megapixels creates larger file sizes, so they take up more room on the memory card.

Card SizeNumber of photos
16 MB10
64 MB46
128 MB94
256 MB188
512 MB380

That last one is pretty impressive. It basically amounts to 10 rolls of 36 exposure film. And here's the amazing part: every single one of these cards is less than half the size of your standard business card.

To illustrate just how small they really are, here is a photo of three types of removable media: an xD Picture Card, a Memory Stick, and a CompactFlash card. I have also included some quarters, so that you can get a sense of size.

The only real problem with this miniaturization is that these cards are VERY EASY to lose. And they don't come cheap — a 256 MB card can cost anywhere from $50 to $100 depending upon the type.

I recommend getting one card that will take more photos than you ever think you will take and then leaving that card in the camera at all times. There have been several occasions when I have misplaced my cards, and when you're talking about 188 photos and $100, that is a LOT to lose!

The Basic Rule of Thumb

When you buy your digital camera, it will only allow you to use certain types of removable media cards. While some cameras let you use two different types of cards, most only allow one. Once you know what type of media you are going to use, purchase the largest capacity card that you think you'll ever need, and use that one all the time.

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