by Agata Urbaniak
For some, “true” black and white photography is synonymous with the black and white negative. Since digital photography is all about colour, digital black and white is sometimes perceived as disingenuous, something that pretends to be something it’s not, a product of nostalgia for the good old times. Why? Because whether you shoot JPG and set your camera to output black and white, or RAW and convert your images afterwards, that’s just what it is – a conversion from colour to monochrome. And since almost all digital cameras are optimised to capture colour by default, that conversion will be inherently flawed.
First let’s get the “colour is much more modern” misconception out of the way. Perhaps you should look at this photo. This could just as well be your mum in her teenage years. A young hippie girl in a red hoodie. This photo was taken in 1913 using the Autochrome Lumière process developed a decade earlier. The presence of colour fools our brain into perceiving it as much more recent. Not old enough? How about the three-color principle first attempted in mid 1800s. And now tell me colour photography is a recent invention. But what about black and white? Are the purists doomed to have to use analogue? Did black and white photography progress at all in this digital era dominated by colour?
2012 marked the release of the first two true-monochrome digital cameras. I must admit I only learned about one of them a little while ago. The other one (or rather its successor) is in my possession. They are the Leica M Monochrom rangefinder and the Red Epic-M Monochrome cinema camera. Director David Fincher, a long-time Red aficionado, used the latter in the production of Justin Timberlake’s “Suit & Tie” video. While most film-makers don’t go beyond ISO 800 unless they deliberately want to achieve a grainy look, this clip has been shot at a whopping ISO 3200. You won’t see any noise whatsoever and the dynamic range is stunning.
Digital sensors are grids of pixels that capture light. But to capture colour, each pixel needs to have a colour filter in front of it. That’s anywhere between 18 and 50 million of them in front of a typical sensor nowadays. This means each pixel can capture the intensity of light in only one colour. The vast majority of digital cameras come equipped with a Bayer filter. The way it works is each 2×2 grid of pixels will have 1 blue pixel, 1 red, and 2 green ones (the human eye is most sensitive to the colour green, hence the decision to use the spare pixel to capture it). Have you ever photographed a concert that’s been illuminated by red lights only? The photo turns out flat and with very little detail. It’s because you’re effectively using only every 4th pixel of your sensor and the other ones are basically doing nothing as there’s no green or blue light to capture. The lack of detail is due to the photo being overexposed and details being blown-out despite the overall impression being quite dark.
Each pixel might only be capturing one primary colour but the resulting image won’t be a mosaic of red, green, and blue. The captured colour information then gets interpolated to create a much wider range of colours. It’s not the perfect workflow but it’s the most practical and widely-used one.
Bayer filter is not the only option out there, there’s also (among others) the Foveon direct image sensor that attempts to use a process similar to that of colour film. In theory it’s a great concept as each pixel is effectively used to capture any of the primary colours. It was also meant to be a remedy for the moiré patterns. In practice, however, users reported poor low-light performance among other issues and the technology never properly took off despite being used by Sigma in a handful of their cameras. Rumour has it, Canon is attempting a similar layered-sensor approach in a 120MP sensor they’re developing. Apparently, anything beyond 100MP using a Bayer filter is a no-go.
Black and white sensor
With the colour process being so riddled with issues, you can’t really expect the quality of a black and white conversion to shine. The sensor is unable to capture the full information from each pixel regarding the luminance, most of it is never registered and therefore is irrecoverable. This is where monochrome sensors come in. The colour array filter is removed altogether and each individual pixel is now able to register the true intensity (luminance) of visible light spectrum. This leads to better sharpness (more detail), higher dynamic range, and amazing low-light performance. Monochrome sensors aren’t therefore less than colour sensors. They can’t register colour but what they bring back into the mix can’t be underestimated.
The good news for photography purists, who want to do as much as possible in-camera and not fiddle too much with post-processing on their computers, is that you can use colour filters intended for black and white photography. That’s right, colour filters used to be vital in the times of analogue black and white, most popular being yellow, orange, and green. Their use isn’t recommended when shooting on a colour sensor as you’re further limiting the spectrum of light being registered. It’s the same principle that’s behind those concert photos I mentioned turning out flat.
But on a monochrome sensor they make sense again. In black and white photography, saturation and hue are irrelevant, only tones matter. It means two very different colours with the same intensity will be registered as the same exact shade of grey, even if our eyes perceive them as light and dark, such as yellow and blue for example. This can lead to dull photos of a scene that could make for an exciting image in colour. By using filters, you’re brightening or darkening certain colours to achieve a better contrast and separation of tones. Yellow, orange, and red will darken the sky to varying degrees (from a little darker to almost charcoal) as well as generally enhance the contrast. Additionally, orange will lighten and smoothen skin tones. Green will make anything on a background of green foliage stand out more. Blue, not being a particularly popular choice, will lighten the sky and darken pretty much everything else.
Monochrome sensor cameras are obviously niche products but it looks like they’re not going anywhere and hopefully will become more affordable in the future. Also, one could hope that new sensor technologies will be developed that will allow for both rich colour and true black and white in one body. What I’m wishing for is a black and white photo printer. Photographic printers nowadays offer up to 11 different pigment colour cartridges, including 2 grey ones in addition to the black one. They obviously offer a much better black and white print quality and richer/smoother tones to a printer with just one black cartridge. It just seems like such a waste to buy a beast like this for printing exclusively in black and white. Wouldn’t it be amazing to have the option of buying a printer with black and grey cartridges exclusively? If 3 black/grey pigments produce great quality, just imagine 5 or 7.
All photos by Agata Urbaniak