>>I don't believe the camera flash would be relevant. The >clock > > >In real world capturing RAW images means more than >transferring a stream data over SDIO line. >
In the real world? Well, I am doing my best here.
I think what you are talking about are all the things that happen before the data is sent to the sdio chip/card. That is relevant only if that front end image data processing, (Expeed), is unable to feed data at wire rate to the SDIO asic chip.
Clearly, the imaging processing engine has a true buffering limitation, based on design, so after that buffer is topped out, it comes down to the chip as it is the last leg before dumping data to the cards in the camera. The Expeed system stalls while waiting on images it has processed into the buffer to be cleared. It has to or it would overwrite data in RAM before the data is written to the card. Therefore, there is obviously signaling that goes on between the SDIO asic and the Expeed system. That is when we see the camera slow down to the speed of the chip/card combo and what I think this memory card speed consideration is all about. Your measurements are indicative of performance of the cards you tried. Fair enough.
I know we can't get to the total bottom of the card issue, as we don't have the real design details, (I checked, we could all collectively pool $5k and get some reverse engineering documentation on Expeed from chipworks).
"Extraordinary claims require extraordinary proof " - Carl Sagan