Personally I just bought the Sigma 50mm 1.4 on my 5D2, since now I finally understand why 50mm was the standard focal length for FF. It's awsome! Much better than the Canon version I tried out. But I should say it front-focused originally, but that was solveable with AF-micro-adjustment.


In your case a 50mm makes more sense in the way that you've already got the 135L for head-shots etc. And the 50mm would make a great upgrade over the 1.8 [:P] (I really hated that lens, also hated the 50mm prime on a crop-body)


Jan