What's the difference between a CompactFlash (CF) Card and a Microdrive? And with CF cards, do the stated speeds of 40x, 80x, etc. work with all cameras?

A: Microdrives are miniature hard drives whereas CF cards are solid-state microchips (flash memory). Microdrives use the thicker Type II CompactFlash format, so they fit in the same sized housing and have all the same connections as CF cards. Their moving parts require more power than flash memory and they're more fragile than CF cards. As long as your camera has a CF Type II slot, you can use Microdrives, but check your manual to be sure your camera supports them.

The 40x, 60x, etc. speed rating on memory cards is based on the data transfer speed that the card will support. The 1x figure of 150Kb per sec comes from the transfer speeds quoted on CD drives, so a 40x card is 40 times faster than this (with a transfer speed of about 6,000 Kb per sec). It doesn't mean it's 40x faster than a standard card though, as that may already be a 4x or 8x card in the first place.

One factor to consider is how fast your camera itself can transfer data. If you have an entry-level model, there's not much point in using the latest, super-fast card. Match the speed of the card to your camera - slowish cards for compact cameras, medium speeds (up to 40x) for high-end compacts and budget SLRs and fast cards (60x plus) for high-end SLRs.

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