About 20

35mm: 7

Medium format: 2

Large format: 3.25 x 4.25, 5x7, 5x12, 6.5x8.5, 8x10, 11x14, 12x15, 14x17.

and a couple of digi-things.

I use most often the 5x7, 5x12, 6.5x8.5, 14x17 and the Contax G1/G2. The digi-things get exercised occasionally as well. I keep the medium format stuff around when I want to shoot high quality color.