I am trying to decide on a 50 mm prime to go with my new 5D Mk III. I do a lot of fairly closeup photography (flowers mostly) and landscapes, so wanted a lens good at both, ie close focus capability, and very sharp across the entire frame. I've been doing a lot of reading about the image quality of the Zeiss 50 2.0 macro and it sounds great. My only hesitation is the lack of autofocus. I don't intend to use the lens for fast action - usually I will have time to properly compose the shots. With the Mark III not having replaceable focus screens, I'm wondering if anyone out there has tried using it with a Zeiss (or other manual lens) and how good the viewfinder image is for manually focusing? I know I could also use Live View for manual focusing, but sometimes that is just a bit awkward depending on the shot.
I am also considering the Canon 50 1.4, even though it has it's issues, it does have very good IQ when stopped down, which is what I often need to do to get better DOF for some types of flowers. A concern about the Canon 50 1.4 is the minimum focus distance on it (18") is about twice the Zeiss (9"). I'm not considering the Canon 50 1.2L, as it appears to have slightly poorer IQ when stopped down than the 1.4 does, and if I'm going into that price range the overall IQ of the Zeiss sounds more like what I'm looking for. I've also considered the Canon 50 2.5 macro, the Sigma 50 1.4 and the Sigma 50 2.8 macro, but can't get too excited about any of those lenses after reading the various reviews. There is just something about the reported mythical image quality of the Zeiss lenses that has me intrigued, not just the sharpness, but also the bokeh appears to be superior to the Canon, and often for flowers I do attempt to get a nice blurred background.
Thanks in advance for your thoughts.