I noticed that, for some of the times when people are discussing on lens, they do not normally specify which camera they use. Different camera, say a SLR to a DSLR, works differently with different lens. A 50mm will become 80mm on a 10D. Therefore a 50mm MKII 1.8 Prime may be better for a 10D user for an event while a EOS 3 user may need something like 85mm 1.8 to get a similar effect.
Just a suggestion.