“DIGITAL for colour, film for black and white, digital simply can’t match the tonality of B&W”.
So goes one claim I have read on the net and, on the face of it, it seems true: black and white conversions from digital generally look flat, dull and unconvincing.
However, it would be odd if, in the digital age, the medium that contains more information (a digital colour photo) cannot successfully mimic one that contains less (B&W film). And it turns out that it can: the problem that digital runs into is the crude, uninformed way in which most people try to make the conversion.
Simple desaturation will not do the job. Curiously, it turns out that colour is very important in black and white photography.
The impact of a well-shot B&W film is often achieved through the use of colour filters at the time of shooting. By filtering out different colours, old-time photographers adjusted their tones: darkening skies, increasing the contrast between clouds and sky, brightening foliage or even making faces stand out from the background.
Twenty years’ dominance of colour film followed by a decade of digital has resulted in these old filtration techniques being all but forgotten. But if you want to convert digital to black-and-white and end up with high-quality results, you have to make adjustments that mimic the use of filters. In Photoshop, that is done by using the Channel Mixer in the Adjustments menu, ticking the Monochrome box and then adjusting the intensity of various colours (to avoid changing the brightness, the total percentage of the three channels has to be kept to 100).
It is also possible to mimic the grain of black and white film by adding Gaussian noise.
Vignetting or fading can be achieved by lassooing the center of the image, inverting the selection, setting “feather” in the Select menu to a very large value and then fading or darkening the edges with the levels slider.
Getting this to look good takes practice, especially getting the balance of the colour channels right. But (of course) there is software out there which will do the job for you at the click of a button. I have NIK’s Silver Efex Pro, which not only offers numerous different styles, it also mimics the grain size and curves characteristics of different black and white films, allows you to see what parts of your image fall into which of Ansel Adams’s different “zones” and instantly mimics the effect of the different filters the old-timers used – red, yellow, orange, green and blue. On top of that, it will mimic various antique photo techniques, such as tin types, cyanotypes, antique plates, pinhole photography etc.
Here is an example of how digital filters can mimic black and white, which also shows the huge impact coloured filters have on B&W images:
This is obviously not a subject where strong filtration is required, the unfiltered version is better than the others. But digital does offer the ability to apply any desired percentage of colour filtration, you are not restricted to the density of the filter on your lens or, indeed, to the four colours in your filter case. That opens the door to infinite creativity (as well as increasing the options for making a complete mess of things).
With all these effects available, is there any reason for anyone to continue with genuine black and white photography? Possibly not, though the fact people want to mimic the medium in digital suggests that the medium itself has intrinsic value. It also takes a lot of skill to mimic film without using an expensive program like Silver-Efex Pro.
On the other hand, working from digital files eliminates the problem of having to scan film, if you are going to use a digital printing technique – and there is little alternative these days.
The ability to create high-quality black and white from digital files exists and the mimicry is so good it will probably fool almost anyone even with a large print. But without using real film and gaining an understanding of how and why different filters and developments are used, few people are likely to understand how to use digital filters to get the best results.
And that, I suspect, is what has given rise to the idea that digital cannot match the tonality of traditional film.