This time I threw in the lions pit three lenses from the past:

• Zeiss Planar T* 50mm f/1.7 for Contax/Yashica
• Zeiss Sonnar T* 85mm f/2.8 for Contax/Yashica
• Nikkor F 180mm f/2.8

Though I understand the importance of bokeh, aberrations, and all other characteristics of the optical items, I first devote my attention to sharpness as a quality I don't want to miss. It is true that you should rather focus on the kind of photo you are taking (portrait? Architecture...?) and the media of the final product (print? What size? Pictures on the Internet?), but remember that the more a lens is sharp, the more you can crop part of the image if it is necessary.
Some issues today can be easily corrected via software, but you cannot invent sharpness were there isn't enough.
In general, this what I look for: sharpness first, bokeh comes second, lack of chromatic aberrations third (chromatic aberrations really make me itch, even though they can be corrected).

The Zeiss Planar 50mm was sub-par, my expectations were high but franly I prefer, by quite a margin, both the classic Pentax-A 50mm f/1.7 and the Nikon AI 50mm f/1.8 (see tests here)
The same person who provided me with the targets also was so kind to lend the two Zeiss optics, and he also pointed out the fact that the where that lens excels is corners in full-frame, that are obviously cut out in my APS-C crops.

On the contrary, both the Sonnar 85mm and the Nikkor 180mm well deserve their excellent reputation, proving very sharp from the center to the corners (remember, we're still talking of APS-C) especially at the wides aperture.
Oddly, both the lenses display some softness coming back stopping down, but I am prone to blame the camera focus-peaking, here, that possibly led me to stop my hand when focus was not the best.
Anyway, the images below speak for themselves, so check yourself.
As most often, I did only test for sharpness (indeed, I have some shots taken to check for aberrations, but I still have to review them), anyway you can find a lot of information about bokeh and aberrations on the web.


All of the lens bodies are excellent from the point of view of construction; the Zeiss 50mm has some minor issues in the focus ring (becomes softer than harder at some point) but nothing to worry about.


Fernando Carello, this nice chap who also happens to be a friend of mine, provides the the targets at this page with detailed explanations (sorry, the language is Italian).

So, here come the crops.
At all apertures, I tried twice to focus properly and only the best of the two shots has been picked for this page.
The four crops on the left are from the borders; the single crop in the single box at the right is taken from the center.
The EXIF data is as good as it can be; the focal length must be ignored because the camera could not obtain it from the manual lens.