Tested on Sony A7 - jpg straight from the camera
I will start with the conclusion, the lens is very very good.
At 1.7 the central sharpness is good and very usable
For landscape at F8 corner to corner sharpness is incredible.
For the price... don't hesitate !
SAMPLES f 1.7
SAMPLES f 8
Bottom Right Corner
Hands down, surely one of the best 50mm I tested
Hope you enjoyed :-)