>Correct. However, a DDR50 mode allows to transfer these 4 bits >two times per clock cycle (during signal rise and fall). Not >sure if this is used in this case though.
Yep, but this is NOT the DDR50 version of the chip according to the spec sheet. I read it closely for the TE4307RXPF, (the chip in the teardown picture). Also, Inrevium does not speak to overclocking the chip.
>More importantly, there is one important part behind the SDIO >interface - a flash memory chip. In real wold is is the memory >chip that defines the real-world performance of a SD card, not >the SDIO signalling speed.
I don't believe the camera flash would be relevant. The clock signal is sent on pin 5 to the SD cards by the SDIO chip and the chip has the smarts, (ie, its own firmware), to determine what kind of card it is talking to. It gets a base clock signal of 25Mhz and has its own clock multipliers that it controls based in the card it sees plugged in. The image below is a basic block diagram.
>No, the results are repeatable. I can consistently take 17 >extra RAW frames when having the shutter button pressed for >30s burst with Lexar 90mb/s card compared to 45mb/s. When >repeating the error is maximum 1 frame.
So to be clear, you are holding down the shutter button, waiting and counting frames for the buffer to fill and timing the results with a stopwatch?