White Balance and Black & White Photography
It may seem counterintuitive to be concerned with white balance in black and white photography. Read on to learn why it’s not.
Back in the early days of photography, all black and white film was “orthochromatic”, meaning sensitive to blue and green, but not red light. This is the reason that blue skies were generally pale, and these areas would overexpose more easily. At that time, film consisted only of silver halide crystals.
But around 1906, sensitizing dyes were introduced that extended the sensitivity of the film into the red spectrum and further into the green spectrum. Similarly, white balance settings will determine the spectrum of colors that become part of the black and white image. Here’s the way it works.
Incandescent light is warmer (more orange) than daylight. So when you set your camera’s WB to “Incandescent” (2700K) it compensates by making the image more blue. So, if you set the WB manually to 2500K, you will in fact be simulating orthochromatic film. (It’s not exact, but pretty close). And if you set the tint towards green, you’re filtering out the magenta component of the reds. Skies under these circumstances will be lighter, and reds will be darker (good for skintones).
At the other end of the spectrum (above 5500K which is neutral color in daylight), if you set the WB to 10000K, it will be most sensitive to red, and least sensitive to blue (and a magenta tint helps too). Skies will be darker and reds will be lighter, resulting in skintones which are more pale.
So, in order to get the most accurate metering and histogram readings, be sure to set the WB for the outcome you’re looking to achieve. This setting will result in an accurate JPEG, but more importantly ensure that the Raw image’s JPEG preview is accurate, meaning that the exposure and histogram are accurate. You can of course change the WB in Raw processing.
If your camera’s CR/LR module comes with a “Camera Monochrome” profile, using that will match the Raw to the JPEG capture/preview. This will give you the most predictable results between the camera’s display and what you see in CR/LR. But it will not give you access to the B+W mixer. However, you’ll be amazed at how much you can alter the tonal qualities by adjusting the temperature and tint sliders in the WB settings.
If you do choose the “Adobe Monochrome” profile (the only profile that allows you to use the Color Mixer as a B+W mixer), you’ll have this feature, and can still use WB Temperature and Tint to manipulate the image.
Here are a few examples of the same image converted to monochrome with different WB settings:
Most camera’s manual white balance settings range from about 2500K to 10000K. CR/LR ranges from 2000K (still not low enough for infrared) to 50000K. Here, one image is shown with a conversion at 2000K and magenta tint (top), the other at 50000K and green tint (bottom). These combinations result in extreme variations in tone.
The follow are combinations that more closely resemble orthochromatic vs. panchromatic film.
This is similar to orthochromatic film.
This is similar to Panchromatic film.
Another way we can visualize black and white conversions is to look at the individual color channels within the RGB image. Here is the blue channel from the above image:
This is similar to orthochromatic film.
With no red or green information whatsoever, this is very similar to an image you would get from shooting with orthochromatic film. If you placed a deep blue filter over your lens and shot a monochrome image, the image would look very similar to this one. You’ll notice the sky has become lighter due to overexposure, and the red barn darker. During the early days of filmmaking with orthographic film, actors would be made up with grease paint to lighten the resulting dark skintones.
Here’s the red and green channels combined from the same image:
This is similar to Panchromatic film.
In this version where we’ve combined only the red and green channels, you can see that the sky is no longer overexposed, and the red barn has become lighter. This would be the equivalent of putting a yellow filter over the lens, because red and green light combine to create yellow. Yes, you read correctly. In the additive color space of RGB, if you were to shine a red light and a green light at the same subject, it would become yellow.
So, a really fast way of converting to monochrome for landscape is to select the red channel of an RGB image, copy it to the clipboard, and create a new image from it, which is the equivalent of placing a red filter over the lens — a common practice in black and white landscape photography. If you have experience with the channel mixer adjustment layer, you can select the blue channel and set it to zero so that no blue information appears in the blue channel. Then, set the red and green channels to 50% each to restore the original luminosity, or use a combination of the two for the effect you’re trying to achieve.
So, now you know why setting white balance correctly is a vital step in successful black and white photography, and how you can use it to manipulate images to achieve your vision.
