Yes I also have Sony’s FE 50/1.8. It’s been named Captain Slow by photozone.de – read their technical review here :) And yes, they’re right!
First, I used the FE 50/1.8 on my A7R – and the auto focus really was unbelievably slow in comparison to my other FE lenses. I now have an A7 II and also upgraded to the newest camera firmware as well as the newest lens firmware (as of September 2016). Guess what? It’s still slow! On the A7 II, it will move forth and back while acquiring focus in the way that the first mirrorless lenses did back in the days where they all did not have any phase-detection AF systems. :p
On the positive side, auto focus is slow but really accurate, no matter where you place the focusing spot in your frame. In my experience, it’s much more accurate than any 50/1.4 on a typical DSLR system is. That’s good. But there’s a catch: For really accurate auto focus, you shouldn’t stop down too much! My impression is that the Sony mirrorless cameras actually have a habit of focussing very sloppy at f/8 or f/11. That’s cause they do auto focus at the preselected aperture – instead of open aperture like any DSLR does.
OK … with the peculiarities of auto focus out of the mind, I can just say good things about this lens. It handels beautifully on the A7 series bodies and delivers nice and crisp images. It’s not an internal focus design but the hood mounts on the fixed part of the lens barrel which is good.
The optics? I can use f/1.8 no problem with many, even demanding subjects. Even over far-away distances it’ll deliver crisp and contrasty images at f/1.8. It does, however, have some field curvature. If you frame a far-away flat landscape, you want to use f/5.6 to get an evenly sharp image. I can live with that. In comparison to legacy 50 mm lenses, I’d still rate the Sony FE 50/1.8 to be optically superior, especially at the more open apertures. It was super good for the A7R and it easily outresolves the “only” 24 MP sensor of the A7 II if you are careful.
With the technical stuff out of the view … I also have to say that this lens makes me appreciate the “plain” 50 mm view very much again! I’ll probably add another blog post shortly about that classic threefold – 35/50/90. These three are probably “my” focal lengths more than all the others!
So here are three of my personal favourite shots that I took with my new 50 so far: