How is the Canon 70-300IS for birds and little league? My budget is all but killing me. The 70-200L F/4 is about 579 and the latter is 549. I've gotten the backyard birding bug so I would think the extra reach of the 70-300 would be ideal. Yeah it's a bit short for serious birding but I can't afford the "big lenses" at this time. I'm also shooting my son in little league. Aside form the low light issue, is that lens suitable for sports? It's gotta be better than the 28-135. Thanks!

