I've now had a chance to use this lens on the A7S and love it. It is a compact, neat lens and super easy to manual focus. It may not be the sharpest at the edges when opened up but it does give, I think, a lovely (non clinical) look to the pictures. I was at a friend's wedding at the w/e and used just the A7s with the 50mm. Here are a couple of shots. The second is at ISO 10,000.