A series of black-and-white images shot in 1976 in Clärchens Ballhaus, a dependable spot for fun in then-Communist East Berlin, shows a night out in fragments, like a soused memory: the ballroom’s grimy looming facade; a bowtie-wearing diner, alone but OK with it; lubricated couples clutching each other on the dance floor like flung-together characters in a Fassbinder movie. When, deeper into “Sibylle Bergemann: Town and Country and Dogs. Photographs 1966–2010,” we encountered Clärchens Ballhaus, 2008, everything and nothing had changed. The photo, in color now, shows a cracked, desilvered mirror