I have a canon 7D, and I will be shooting lots of rock band in concerts, low light or lots or color lights and spots, what lens would you recommend, i was thinking about the canon 50mm 1.4 or sigma.

I dont want to use a flash if its possible,

and I will be able to be walk freely all around musicians and stage. so distance wont be variable.

thanks

also what settings would you recommend

I only have right now the stock lens 28-135mm