I had actually set out with the intention of doing a few test shots with the Zeiss Biogon, to get a feel for how the lens draws at various apertures. It wasn't long after leaving the house when the fog rolled in again. I went with it and took a set of photos anyway.
Here's a link to a NEX-5N RAW file taken with the Zeiss 35/2.0 at F2.0. Bokeh or fog, you be the judge.
The Zeiss is a joy to use: it's size and weight is a perfect match for a compact camera body. The precision machined, solid metal lens barrel feels luxurious compared to the hollow plastic or aluminum “cans” I normally use. The focus ring is smooth with just enough resistance and the apertures click into place precisely and firmly. I found the aperture ring's placement at the front of the barrel odd at first, but have come to like it. It's easier to see and set the aperture and I also like the clear separation of aperture and focus control. There's no groping around in search of the desired ring.
Focusing the Zeiss manually is also turning out to be easier than I thought. In the past, I've had trouble focusing lenses wide open. Now I realize that was due in part to the fact that these lenses had low contrast and/or sharpness wide open. That made it very difficult to see when I'd achieved critical focus. The Biogon, however, is sharp enough wide open that in-focus areas pop out in the viewfinder. Also the camera's focus peaking function has high contrast detail that it can grab on to.
Combined with a good screen and viewfinder, a lens that that's sharp and has good contrast can be focused quite efficiently.