Does anyone carry an 85mm on a crop? How often is it useful? I was thinking of picking up the Canon 85 f/1.8, primarily for taking photos of surfers and such where my cheap 50mm's AF can't keep up. I might use the 35mm f/2 in more situations, but I already have a 24 and 50 so I can't decide if I'd rather have a telephoto.
Or I could just get nothing. The 24 is all I need in 85% of situations.
Assuming you're using a crop body at 1.5x I'd have thought 85 (roughly 130 equivalent on FF) would be too short. It depends how close you can get. A cheap option would be an adaptor and one of the better manual focus 135's (most of them are decent even on a modern sensor) which would give you roughly a 200 equivalent.