A tad off-topic, perhaps, but I've been very happy with the screwmount "Winogrand" Canon F2.8 28mm. It has been my "standard" lens since the early Sixties. It's not tack sharp all the way when zone-focused, but it has its charms, on which Sean Reid has commented favourably. I had Peter Grisaffi of CRR in Luton do it in black paint to go with my M2, and it will become my standard lens on an M8, should I ever get that lucky. It's so compact with a cap on that people assume it's an Elmar, and try to pull it out. And the front element is so deeply recessed that no hood is required.