I searched the forums a bit and came up empty on the bit depth or A/D converter for the camera. Quick check shooting a raw with most everything turned off (to minimize any processing) than inspect the histogram. Not just visually but actually get at the numbers. Pretty straight forwad to see how big the jumps in value are and then figure the A/D converter bit depth. In my case the software I use stuffs the data into the upper bits of 16 bit data word. Max value/jump gives the number of unique values. For the E-P1 there are 1024 unique values which equates to 10 bit A/D converter. It certainly is possible that there is something else in the camera but if the lowest level of access is through minimally propocessed raw images then 10 bits it is for all practical purposes. Pretty much any image histrogram will reveal this info unless completely blown to white (saturated) for every pixel.