It's an old cliche, with the forest and the trees. But it applies here, cliche or not. I've been on a 50mm diet for a while and I've used way too many 50mm lenses for my own good.
The diet wasn't for fun or meant as a useful exercise to optimize shooting with just one lens. No, it was to compare a bunch of lenses for this site.
First there were the Panasonic Leica 25mm f/1.4 and the Olympus 25mm f/1.8 for Micro Four-Thirds (equivalent to 50mm in full frame). Then there were the Zeiss Otus 55mm f/1.4 and the Sigma ART 50mm f/1.4. On top of some lenses I already owned in that range, I also rented the Canon 50mm f/1.2. That was a lot of fifties.
TL;DR
I was planning to write a long piece comparing all these lenses, but concluded it falls under that internet term TL;DR (for Luddites: Too Long;Didn't Read). I wouldn't read it myself. I'm the kind of person who has never read a full review on DPReview, the kind they hate because I jump to the conclusion and deprive them of all those hits in between.
Also, I want this site to be about the real world. And for enthusiast photographers pursuing art or beauty, not necessarily technical perfection. Most people don't see technical perfection if the image is strong enough.
Yes, people see flaws. But we're not talking lenses here that come in the camera kit or sell for a token. We're talking basically good glass and go up from there. Any of these lenses will do the job.
Oh, and there are no pictures with this post, other than the one above to remind me of the nervousness I felt having that loaner Otus and the Sony A7r sitting on that slanted rock next to that stream. There are no other pictures because I'm just really bad at producing good shots when I'm constantly switching lenses. I've got tons of pictures of my kids, which I don't publish as a matter of principle. I've got tons of comparison pictures, but they're boring, boring, boring.
Quick Overview
So, I'm going to make this quick:
the Canon 50mm f/1.4: good workhorse for a decent price; doesn't work with the Metabones III adapter on the Sony A7(r)
the Zeiss Planar ZE 50mm f/1.4: a bit warmer colors, a bit more contrasty than that Canon, but manual focus only
the Canon 50mm f/1.2L: the lens to have until the Zeiss Otus and Sigma ART entered the stage; you can do awesome things with f/1.2, but unless you really need that wide an aperture, you're better off with the Sigma at lower cost
the Sigma 50mm f/1.4 ART: great lens for a decent price; a bit bulky and long, whereas the f/1.2 is just bulky; the one to go with nowadays unless you want to squeeze the very last out of your camera sensor, in which case you go with
the Zeiss Otus 55mm f/1.4: top quality in all regards, with the price to match; large, heavy, impressive. Manual focus only, though.
Of the latter three lenses, the Sigma renders a bit warmer than the Zeiss and the Canon. The Canon shows more chromatic aberration than the Sigma. The Sigma shows more chromatic aberration at f/1.4 than the Otus, but it disappears in both as the aperture narrows.
If you want this focal length for your Sony A7(r) instead of a Canon DSLR, I'd opt for the excellent Sony Zeiss FE 55mm f/1.8 instead of using the other ones with an adapter, which slows down operation. The exception is the Otus, which is manual focus on either camera and really makes the 36 megapixels of the A7r shine.
Truth is, unless you're doing really critical work or work under really challenging light, you're not going to see much of a difference on the final prints between the top choices. But if you are that perfectionist, save up for the Otus or buy the Sigma for Canon or the Sony Zeiss for the A7(r).
By John van Rosendaal