Hu'u Bar on Sathorn (ascott building, right after the narathiwat conjonction when u come from sathorn then it's on your left 50 m after the red light).
They hold photo exhibition time to time.
Tonight have a new exhibition.
Then as Marc said Bkk magazine or Guru have full of adress for the cultural event and location to see exhibition in Bangkok.
Ask to speak with Tan, he's the gentle owner

Fred