So, what are analog photographers’ contact sheets actually ‘Proof’ for, aside from the fact that shot wasn’t fished out of three thousand accidental digital snaps? A Chicago gallery is assembling great photography alongside the original contact sheets. Go and see the frames of intent, acrobatics and voyeuristic prodding from the contact sheet diaries of 26 photographers. “Proof,” group show, Jul 16 – Sep 4, Catherine Edelman Gallery, Chicago