just looking at the lengths she has i would look for a zoom to give her options.?.?
thats the plan
my lens list...
18-55efs
50 1.8
100 2.0
10-22 efs
to be honest, the only lens I'd like to add is either the canon 70-200L or the IS version.
outdoors- 10 22efs(landscapes, some misc shots), 18-55efs (which is a good lens IMO)
people indoor stuff - 50 1.8, 18 55 efs
shows - 50 1.8, 100 f2 (both are fine for smaller shows/club setting)
outdoor people - once again the 50 and 100f2
the only area Id like to cover is indoor/outdoor sports/recitals/plays etc for my neice/nephews, however I get away with the 100mm (160 on a cropped body) but I'd love to have something longer. Adding the 70-200 would fill any gaps I have.
I find the Canon 100m f2 to be spectacular for most of the things Ive been taping (small clubs, bars etc) and it is VERY compact. Plus it's fixed so I think the images are a bit sharper.
I'd say bite the bullet and go for the sigma 70-200 or the canon IS or non IS. Sure they are out of your budget for now, but you can use them into the future with body upgrades. You have a fairly wide 18-55 efs and a fast 50, so I dont think you'd lose too much by skipping over the 50 to 70 mm range and jumping to a lens that 5 years down the road you wished you'd had all that time... The only downside is if you move to a non-cropped body whereas the efs lens wont work which is my situation if I ever went full frame, but then I'd just keep my xti and use the 10-22 with 18-55 on the second body..