OK so I just got my T2i and the 18-55 kit lens and am looking at either the 24-70l or the 24-105L. I currently use a Canon XH-A1. I have never used an L series lens and was wondering if the zoom and focus will be as smooth as the lens on my XH-A1? Thanks.
My advice would be to hire them first just to be sure, unless I'm mistaken Canon hasn't made any lenses (for their DSLR's) which are optimized for video. This may take you a while to get used to.
This is like an unspoken area of Canon DSLR filmmaking. I dont have any problems manually zooming with my lenses as long as the camera's secured to a strong video tripod.
I like the 18-55 lens. I can zoom very, very slightly with it before the aperture automatically shifts gear.
There are some issues with zooming on dslr lenses especially because they are not parafocal (they change focus when you zoom). The best way to avoid this is not to zoom . Those lenses you mentioned are nice, but they are geared tword full frame. If you plan on stepping up to the 5Diii when it comes out next year, it may be a good idea, otherwise there are other options to look at. 24mm is not really wide enough on APS-C sensor (T2i) (the 17-40F4L is actully better on a T2i IMHO (plus a fast 50)). I would look at the Canon EF-S 17-55, the Tamoron 17-50 VC or the Tokina 16-50. Do some searches and see what you can find here. Don't be in a hurry to buy and do your homework for a few days first.