Originally Posted by tybeck
I don't have the 50-135mm, but I've found 50 mm to be the minimum focal length for this kind of shooting. Less than that is only good for crowd or wide stage shots.
I second this. I did a punk rock show with my SP-F and thought I'd bring my 55/1.8 with me as my standard kit. Turned out to be a total pain. Couldn't get close enough, and the flash was too bright when I was. I think the sweet spot here would have been 85-105mm or so, so I could get close enough to the performers without getting that close to them or getting in the way of a mosh pit (mosh pits + cameras don't mix).