« on: July 21, 2013, 04:58:33 PM »
I have this lens, I think the IS may be more like 3 stops. I haven't had the experience of the 1.4, but I bought this over the sigma for the size, weight, and reliable af. AF is super fast, I dont know where you got the idea that it was slower but it seems like its at the top of the heap for lens af I have used(well out of 24-105, 70-200f4 and 135).
It does vignette quite a bit, also the plastic construction, not an issue to me, people gush about the EOS M's construction but they feel similar to me, its well built and leagues ahead of the 50 1.8. For me the real cons are the coma, it is pretty terrible for astrophotography, and obviously price.
I bought this mainly as a primary walkaround lens for my 5d3, and I think it fills that gap rather well.