MultiMediaCards (MMC)

MultiMediaCards (MMCs), though slightly thinner than Secure Digital cards, are the only type of removable media format which can interact with another format (SD). Most manufacturers are building SD slots into their devices instead of slots for MMCs, because the SD format offers faster read/write performance. However, because MMCs fit into SD slots, don't be afraid to purchase this type of media to use with SD-based digital products.

MMC cards are available in the same sizes as SD cards, and with very similar pricing until you get to the higher capacity cards, with a 4GB unit costing roughly $170.

Memory Stick Pro Duo

Despite being used predominantly in Sony products, Memory Stick media could be the best bet for digital camera buyers with other Sony devices.

Designed for use with both PCs and a wide variety of digital AV (audio/video) products, the Memory Stick can be used to store, transfer and play back AV content such as images, sounds and music as well as information including data, text and graphics. These days they are compatible with everything from Sony Ericsson phones through to the Playstation Portable. Memory sticks used to be a little larger and thinner than SD cards, looking more like a stick of gum than a postage stamp, but the now commonly used Memory Stick Pro Duo is a much smaller format, and comes in a little smaller than a standard SD card.

The only problem with memory stick technology is that no other companies really support it. Sony is the only camera company to make use of it, and while you may find the odd third party electronic device that supports it, for the most part you'll be stuck with Sony products.

Memory sticks are a little more expensive than their counterparts, with a 512MB card going for around $30 to $35, while a 4GB unit costs about $90.

xD-picture card

The other major memory format is the xD card (Extreme Digital). Two of the companies behind the SmartMedia card format, Fuji Photo Film and Olympus, made the switch a few years back, developing their own format of flash memory.

The xD-Picture Card is only 20x25mm in size and a little thinner than the other formats. However, it also costs a little more, with a 512MB card costing about $30 and a 2GB card is priced at $130. Currently xD cards don't extend to the same capacities as CF or SD cards.