[wim]

I had the same problem with the 70-200/2.8L IS that I have, very often I was forced to shoot at wider apertures due to poor light, and ended up with not enough DOF for real life shots (especially theatre - thankfully I don't do that one anymore). Say, I had to use f/3.5-4 to eke out decent shutter speed, where f/6.3-8 would be a minimum requirement for getting more than a part of one actor's face in focus. And no, it was not always possible to get closer and use the 16-35 instead (apart from the fact that I'd be getting a very different perspective - disjointed, for a lack of a better word).

I have one f/1.4 lens but I'm mostly using it in very lousy light. Ironically enough, it's the least accurate of my lenses AF-wise in such conditions - it incurs a noticeably higher degree of OOF shots (including completely blurred ones) where the 16-35/4 just gets there (albeit with some struggle at times). The lens in question... 24/1.4 L II. By the way, if anyone has had the same experience as me, please tell me - I'm eager to know if something is wrong with my copy, or it's a common trait of this model... (but no, I'm not ready to put it on the chopping block - when it is in the right mood, it's making wonderful shots).

 

I own a 2 4 F/1.4L II - no problems with focusing, not on any body I used with it (40D, 5D, 5D II).

 

HTH, kind regards, Wim