Leica vs. Zeiss
Very old Zeiss lenses (pre-Contax SLR) are said to offer a “plasticity” in the image unavailable from Leica or Japanese lenses, due to the different optical design. But this image illustrates a clear 3-D quality (view large) like an old Sonnar, even though it was made with a Leica lens and 2X extender.
According to Erwin Putts, Leica lenses were designed for maximum sharpness at the focus plane, while old Zeiss lenses were designed for a smooth transition from the focus plane to out-of-focus areas. Evidently that difference in design is irrelevant to the three-dimensional quality of the image.