There are many different kinds of memory cards. CompactFlash (CF) and Secure Digital (SD) are the two most popular formats. They are not interchangeable. The following buying guide specifically addresses CompactFlash cards. But the advice holds true for Secure Digital cards as well.

Other memory cards such as xD and Memory Stick are also available in different speeds. However, write speeds are classified differently.

Cameras that use CompactFlash cards accepts either type I or type II CF cards. Type II is slightly larger.

Most CF cards you encounter will be type I. Type II is generally used for Wi-Fi cards and other add-ons. These add-ons are for use with handhelds and other gadgets. So don’t worry about the difference between the two sizes.

Additonally, Microdrives use the CF type II size. Microdrives look and function much like CompactFlash memory cards. But they are actually small hard drives.

I don’t recommend using a microdrive. They are more susceptible to failure because they have moving parts. They also eat up power.