I can't find a way to do it either. 
and now, for your moment of (my)
zen
Canon 5D, EF 17-40mm f/4L, EF 24-70mm f/2.8L, EF 135 f/2L, EF 70-200mm f/4L, EF 85 f/1.2, EF 50mm f/1.8, EF Extender 1.4x, Bogen / Manfrotto 190XDB w/ 486RC2 Compact Ballhead and a lot of studio lighting.