Something unusual happens when a photographer known for empathetic portraiture of the marginalized focuses his incisive eye on the lifestyles of the rich and famous. In the wildly diverse and revealing Bruce Davidson: Portraits, we see Joan Crawford hell-bent on force-feeding some poor soul, Diana Ross and The Supremes having a snowball fight, and an intense Samuel Beckett during a rehearsal of Waiting for Godot. Seen through Davidson's lens, Newt Gingrich is as goofy as Bobby Kennedy is impenetrable.