>>Hmmm....Canon tech support advises only to use 133x card due to error prone faster cards...also that a 16 gig card must be read entirely first to find avail. blocks, hence use the smaller cards. Am I wrong to believe technology is simply not here yet to not have a camera hang after depleting the buffer, since no card can write fast and reliable enough to prevent the buffer from filling?<<
Hi, Paul:
You may have misinterpreted part of what Canon's customer support was saying about the choice of memory cards for the 1D Mark III. The camera does not support UDMA, which means that there's a limit on the data transfer speed when writing to the card. Because of that, if the camera's card writing speed is the only consideration, ultra-high-speed memory cards won't make much of a difference if any in terms of camera performance.
FWIW, I have not been hearing any complaints about data errors with the 1D Mark III, either through my own professional photographer contacts or through CPS. If this were a chronic problem, it would have been widely reported by now. Also, the 1D Mark III is clearly compatible with a wide range of memory cards with speed ratings exceeding 133X, as shown in Rob Galbraith's online database for CF and SD card performance.
Rob Galbraith DPI: Canon EOS-1D Mark III
As you noted, this table shows that the 1D Mark III's card writing speed is limited to approximately 10MB per second with CF and 14MB per second with SD. That's nowhere near the transfer speed capability of the high-speed cards themselves, as shown by their performance when connected to a personal computer with a high-speed card reader. In some cases, you could be looking at transfer speeds of 30MB per second or more, so in this context, the camera is clearly the limiting factor.
On the other hand, a slow memory card like the 5MB per second example you mentioned could very well reduce the 1D Mark III's burst rate below its maximum potential. Coming back to your original question, there is no doubt that using a higher speed card could maximize the number of shots per burst. But it should be clear that the best you're going to get under any circumstances with the 1D Mark III is approximately 33 to 36 RAW images per burst at 10 fps. In other words, once the card speed exceeds a certain point, the camera becomes the limiting factor as I previously mentioned. And conversely, once the card speed falls below a certain point, it becomes the limiting factor instead.