Archived from groups: rec.photo.digital (More info?
The 20D has an internal buffer to hold pictures until written to CF
card. So in actual shooting you will not notice a difference until the
buffer fills and writes to CF. If you shoot and store both RAW and
JPEG at the same time, you would fill the buffer after one second of
continuous shooting at 8Mpixel! So if you're shooting sports, you'd be
concerned about reducing any wait time to continue shooting. If you're
simply shooting a graduation, you'd not care and maybe settle for
mid-speed. If you're a landscape photographer, go with the slowest!
It depends upon your shooting needs as to whether or not you spend the
money for faster CF card. 1MB for $50 (normal speed), $75 for 40X,
$100 for 80X, typical web quotes. Pick your poison depending upon your
shooting needs. As another post points out, the speed may also matter
if you have a CF full of pictures and are downloading to your PC, and
are impatient for the download time.