peevee1: "The E-M1 devotes every 16th pixel to autofocus duties, arranged in offset stripes of left and right-looking pixels. The focusing pixels sit behind clear sections of the color filter array to increase their capability in low light and do not contribute to the final image. "
That might be a preview of Sony technology soon to be seen in new NEX and Alpha cameras.Not contributing the extra light to the image is just stupid, and using just 1/16 does not seem enough.
@peevee1 contrast based AF is still there and it receives the rest of light. PDAF needed to get the lens movement direction right in the first place.