A few months ago I had a fun opportunity to compare the Leica Noctilux 50mm f1 versus the Voigtander Nokton 50mm f1.1 versus the venerable Carl Zeiss C-Sonnar 50mm f1.5 ZM. All lenses were compared wide-open at their largest apertures. Here is what we found.
Sharpest: The C-Sonnar is the sharpest lens wide-open, followed by the Nokton and lastly the Noctilux.
Bokeh: The smoothest bokeh crown is owned by the Noctilux, followed by the C-Sonnar and the Nokton. Though the C-Sonnar is slower, the bokeh more closely matches the Noctilux's character, just with a few stops more depth of field (DOF).
Overall image/look: The Zeiss "Pop" is alive and well on the C-Sonnar. Turning-in the best transition from in-focus and sharp subject ( in this case a pint glass) to out of focus areas and creamy bokeh. The Nokton does a commendable job with both sharpness and shallow depth of field bokeh, but with slightly busier bokeh than that out of the Noctilux; its closest competitor. The Noctilux, well thats a look completely unique and a class all its own. The bokeh is creamiest, it has the least "Pop" and is also the softest wide-open with a classic glow that most people love.
Overall, the winner in my eyes and best value for money, if you are biased-towards attaining shallowest DOF, would be the Voigtander Nokton 50mm f1.1. It isn't the sharpest wide-open, but still sharp and considering it has 1.1, 1.5, 1.8 aperture stops, the easiest to sharpen-up without gaining too much DOF. Furthermore, stopped-down to F1.5 (like the C-Sonnar) it could no doubt get close to/match the C-Sonnar's performance wide-open. However, for portraits, daylight shooting or film photography, my choice would be the C-Sonnar no doubt.
In the used market the Nokton's sell from $650-$750 ( I got mine for $460 however). The C-Sonnar is $800-$850 and the Leica Noctilux f1, well they go for $5,000 used. The newer and faster Noctilux f.95 sells for $6,800-$7,000 used and perhaps would provide the sharpness of the C-Sonnar or Nokton, with undoubtely creamiest bokeh of all.
If price is a factor, the Voigtlander or Carl Zeiss Sonnar are both excellent choices for a fast 50mm lens that are built well, provide an image full of character and all for a fraction of the price for the Leica Noctilux. Are there other cheaper, excellent 50mm lenses out there? Yep! And we will follow-up with a wider ranging comparison here soon.
Contributor Pocholo Francisco had these thoughts...
I agree with your technical assessments of the lenses but I have to disagree with your final conclusion in that I actually think the best value is the Zeiss 50mm C-Sonnar. Mainly because it definitely has character and is compact for everyday use and is also a pretty fast lens for night shooting. If, however, you're in the market for a low light lens for use with a film rangefinder then the Nokton is a good value for that. I just don't believe you need that fast of a lens for low light, especially with the low light abilities of the modern sensors. The Noctilux and Zeiss run away with the most character and for me the Noctilux definitely has the smoothest bokeh of the bunch.
Test samples available here and below. All shot wide-open tested on a first-gen Sony A7S.