The 15MP Sony IMX521CQR sensor was first leaked several months ago. Now since Sony a7S III is rumored to be announced soon, it is very likely that Sony a7S III will use this 15MP IMX521CQR sensor, you can take a look at full specs sheet of IMX521CQR below. Sony a7S III will shoot 4K60p video, and a possible of 61MP mode.