The Sony 35mm f2.8 is by far my favorite lens. I've been using it for a while now, and here's my honest. I'll tell you why I like it so much, and why it might not be for everyone.
First off this is a Carl Zeiss "MY MAN!" lens. Which mean that like every other Zeiss lens, it's super sharp, even at f2.8. It gets insanely sharp at f4, like the quality level that you don't often see! This lens is definitely made to mount on the Sony A7R series since they have an extremely high megapixel sensor. The only issue with the optic is that it's always much sharper in the center than on the edge, as you can see from theses test from DPReview. It doesn't mean that the edges are soft by any means, but when you zoom in on your photos, there's always a notable difference in quality from the center to the edge. You really notice it because the difference in quality is inside a single image.
Since I shoot mostly at night, I was worried at first that f2.8 wouldn't be adequate the capture enough light in dark situations. But modern sensor let you underexposed so much and bring back the shadow in lightroom, that's it really not an issue. I always shoot one full stop underexposed, and sometimes when I'm in streets with enough neon lights, I can even crank up the aperture at f4 while keeping the iso at 100 and the shutter speed around 1/50.
But the best feature of this lens, right after the quality of the optic, is its size. For years I've used lens that was often around a kilo. The fact that Sony decided to go with a max aperture of 2.8 instead of 1.8 or 1.4 really helps to keep the weight down, and also the price! And usually, with f1.4~1.8 primes lens, I always shoot at least at f2.8 or more because I want sharp photos. Any Sony A7 camera with this lens on it weights less than a kilo together and can fit in a coat pocket. This is actually a major plus for me.
The only reason I could see someone not wanting this lens if they are looking for a 35mm would be if they are looking for a portrait lens. Subjects look fine with this lens, but you are not getting the nice blurred background with smooth bokeh that a more expensive, bigger aperture lens could give you.
But for street photography, portability, and optic, this lens is king!
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