I'm not exactly sure, for I don't work in such an industry, but it's logical to assume that they take the memory size of the buffer and divide it by the average size of a photo. In other words, they do not factor in the rate at which data is written into the card.
Originally Posted by pwnage101
Maybe, maybe not. Depends whether it is the official specs, in which case it should almost always be higher in reality, >6. If you take the data from their "performance" section, it would most likely represent the number of shots per buffer in acutal situations.
so when I read 6 raw frames in a Nikon d80 dpreview, that can change with a faster/slower card?
In the case of a d700, the actual number of shots taken with a slow card is 17. A fast card increases this value by 2. Refer to the water tank analogy for the explaination.
Burst of RAW images (12-bit NEF)
(4GB SanDisk Ducati)
(2 GB Lexar 133x)Frame rate 5.0 fps 5.0 fpsNumber of frames 1917Buffer full rate 2.2 fps1.1fpsNext burst11.0 secs21.0 secs