Side by side, clickenzee to Embiggen!
There's definitely a difference wide open in the bokeh -- the Summilux is a lot smoother. It's also half a stop brighter and the color is a bit different. And the Summilux focuses closer, which is a distinct advantage, though it's also significantly larger and heavier.
In the 100% crop it seems a bit sharper but at this aperture it could also be a focusing variation as well.
My ultimate conclusion is that the Summilux, while nice, isn't $1,200 nicer than the Serenar.
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