A recent post on dpreview forums asked what the affect of shutter time had on frame rate of the 20D, so I took some measurements to see for myself.

Each burst recorded was a total of 5 shots, measurements were taken between shots 3 and 4. Each burst was done three times, if any disparity existed in time measurements the middle value was taken (The burst closest to the middle of the measurements, not the average of the three). Measurements are +/- 1 ms. The measurement of interest is the red "2-1=xxxms" value at the bottom of the sample window.

Since the measurements were done between shots 3 and 4 of a 5 shot group the 27 shot buffer was never tested, and thus the write speed of the card did not enter into the measurement at all. However, because I know someone will insist that it would matter, I did pop in a couple different types of cards, Lexmark 80x 1 GB, SanDisk 1 GB Ultra II, and plain old Sandisk 512 MB just to make sure, and there was no difference across those cards.

Camera was in Manual mode, aperture was set to f2.8 (wide open for the 70-200 f2.8 L IS I had mounted), shutter selected as needed, Fine JPG mode, MF, IS Off, lens cap on (the lens cap on is the ONLY way to measurebate).

After that, someone questioned if the 20D could maintain 5 fps in AI Servo mode, so I checked both that and AI Focus mode. It did not do 5 fps in either, anything from 3.2 to 4.1 was the norm.