Here another 50 mm (more or less) battle. Always on the Sony A7. A Sony-A7 dedicated lens (Sonnar ZA) vs. a Leica M-Mount lens (Planar ZM).
Let’s start with focus at infinity and f/2 for both lenses.
In the center zoom at 100% (click for full size):
Both are sharp but the ZA seems to have a slight edge over the ZM.
On the border of the same picture, zoom at 100%:
We know that ZM lenses are not optimized to work on the Sony A7 and this becomes visible on the edge of the sensor. As a matter of fact the ZA is much sharper. However by closing the aperture to f/5.6, the Planar ZM shines and outperforms the ZA also on the border of the frame (ZM now on the left):
Let’s look at a bokeh test. IMHO both lenses have a beautiful bokeh at all apertures.
At f/2 (click for full size):
Zoom in at 100% at f/2:
As in the infinity test, the ZA is slightly sharper.