Usually the rate limiting step is analogue-to-digital signal conversion. The conversion rate ranges somewhere between 1 and 20 MHz (pixels per second) for 10 - 16 bit converters (16 bit data) in most cameras. This is slower than the data transfer via FireWire (IEEE-1394) would allow: 400 Mbit/s = 50 MB/s = 25 MHz (pixel per second). This would equal more than 17 full frames per second for 1376x1040 pixel images.