The topic of this thread is timely for me. I rented the 50L this weekend and have taken a few intial shots. BTW, I own the 35L and the 135L which are great and sharp lenses. I've also rented the 24L II and was very impressed with the IQ and will get this lens in the spring.
Back to the 50L. It's rather soft at 1.2. From f2.0 on, the lens is sharper and the colors are very nice along with the contrast. I have yet to shoot outdoors. My intial reaction is not positive and hopefully, my mind will change. When I evaluated the 85L II, I was blown away. I'm not getting the same reaction with the 50L. Any tips, tricks regarding this lens would be appreciated from owners of this lens.
I would have to say that the 135L is the sharpest with the 35L second and the 24L II third. The 85L II and hopefully, the 50L are in a different category.
My 85L II is super sharp, but my 50mm is no slouch either. I use the 50mm a lot more, the minimum focusing distance on the 85mm can be somewhat limiting in certain situations. The 50L is definitely a little more versatile, I usually use the 85 for portrait stuff.
I would go shoot some outside with the 50L and play with it some more, and maybe try another copy if something looks way off. I know I've prematurely judged lenses before when I would just pop them on in the office to take some "test shots." But none of the test shots ever end up being something I would have photographed normally, so I think its better to get out there and try to shoot something "unrehearsed" and see how you like it after that.
And f/2 is definitely the sweet spot, and be mindful of short hyperfocal distance when shooting at f/1.2.