Just consolidating some information here from what I've read as I find this thread highly intoxicating, despite not owning a 5D3.
Correct me if I'm wrong here, but a RAW frame will be composed of R, G, & B channels. However since the data is not debayered, R & B are 1/2 the horizontal and vertical resolution of a debayered frame, thus 1/4 of the frame's resolution is color data for either R or B. And since G is twice as pixels than either R or B, it'd consume 1/2 of the frame's resolution is color data. Overall, this add's us to just the pixel count of what a frame is. Now, this is 14-bits per pixel data, 8-bits in a byte, 23.976 fps (simplified to 24 fps for the sake of simplicity), frame_res*14/8*24= datarate in bytes/sec.
If my understanding of the data format is sound then this is what follows so far...
For the 5D3 with the KomputerBay 1000x cards being used, we've seen:
1920x900 @ 24 fps --> 1,728,000 pixels, 14 bpp @ 24 fps --> ~69.2 MB/sec write speed requirement
1920x1080 @ 24 fps --> 2,073,600 pixels, 14 bpp @ 24 fps --> ~83.1 MB/sec write speed requirement
1920x1152 @ 24 fps --> 2,211,840 pixels, 14 bpp @ 24 fps --> ~88.6 MB/sec write speed requirement
For the 600D, the reported card I happened to miss, we've seen:
1280x400 @ 24 fps --> 512,000 pixels, 14 bpp @ 24 fps --> ~20.5 MB/sec write speed
960x540 @ 24 fps --> 518,400 pixels, 14 bpp @ 24 fps --> ~20.76 MB/sec write speed
CF and SD cards are Flash memory. There is a bit of a principle of Flash memory that *will* affect your write speeds, and though these memory cards are not what we consider SSD's,
they have to abide by the same rules.
In order to provide a proper test, also to ensure your CF/SD card wears evenly, which not all manufacturers use or advertise if they have wear leveling, you should format your memory card in a computer with a "Full" format to make sure you get real world results. Initial writes may be faster, but that won't be how the rest of the card performs during the rest of it's life.
