I would like to add two new dimensions to this (old) thread and discussion. The review of “bokeh” should be done separately for colour and b&w photography. It is a common error colour photographers make to assume that their lens-kit is any good for black and white photography. It is not. Rather I would advise they re-considered all their lenses from the beginning if venturing in serious B&W photography – and assume everything they know about which lenses are good to be irrelevant.

The second dimension of bokeh in black and white photography is called “modelling”. A term colour photographers and generally photographers under 70 years old are not aware of, because they know little about black and white lenses. The holy grail of B&W photography is not “bokeh”, but “bokeh modelling” – that is: the three dimensional rendering of out of focus objects as a result of structured (and not smooth) bokeh. The quality of modelling does not help the background dissapear into a smooth cream as in colour photography, but it disolves it into smooth, but eligible shadows, gently describing what was there before, informing the viewer of the background scene, while still helping isolate the subject of the photograph. In colour photography this effect is done through colours instead.

To summarise the goal of lenses designed before colour film was invented is not smooth bokeh – it is structured modelling – which is why Leica lenses before the 60s all render with strong modelling – not because Leica didn’t know what they were doing back then.

For examples of what I mean by this, look for photographs made by the Leica Elmar 50mm f/2.8, the Leica Summaron f/2.8, the Leica 35mm Summicron IV etc on flickr. In my view the Elmar 50 f/2.8 is one of the most extraordinary lenses for b&w photography (here rated 3). What I love about it is it’s outstanding bokeh modelling and incredible tone rendition (another concept colour photographers know little about).

Examples from other photographers:
https://www.flickr.com/photos/centir/11395274916/ Elmar
https://www.flickr.com/photos/sonicinfusion/6471421157/ Elmar
https://www.flickr.com/photos/jbiel/5534913352/ Elmar
https://www.flickr.com/photos/michael_sergio_barnes/8302021625/ Summaron
https://www.flickr.com/photos/chunyang/8700386699/ Summicron IV