The 90-Percent Rule—Part Two—Tone on Tones

[rolandogomez]

In Part One we learned the 90-Percent Rule definition as whatever is pure black, will absorb 90-percent of the light that hits it, whatever is pure white will reflect 90-percent of the light that hits it and that there is 10-percent light reflected from pure black and 10-percent of the light absorbed from pure white. We also learned how we can apply this photographic principal to flash incidental metering when working with models and artificial lighting.

In Part Two, we’ll explain how you can use the 90-Percent Rule for proper illumination of white in high-key scenarios and the proper exposure of black in low-key applications. First, let’s look a the 90-Percent Rule more closely, we fully understood how we use the “reflective” part of the rule in Part One for flash metering, now we’ll look at both reflective and absorption of light together and how we can apply this to shooting similar tones on tones, or black on black and white on white.

Normally when photographing black on black, or a dark subject against a dark background, the subject will appear to disappear into the background, a sort of fusion. Sometimes this makes for interesting photographs, but most of the time it’s more appealing to see a separation of the subject from the background. This separation will also make your subject stand-out or appear in front of the background—this is important in that photography, like many art mediums, is a two-dimensional result and since we see in three-dimensions, this separation will help with creating a third-dimension illusion.

First, let’s take white on white. The key here is to take at least two, black panels and place them on each side of the subject as close as possible without intruding on the frame of the image. These black panels help subtract light from the sides of the subject while reflecting some black light back into the subject’s sides. This affect will create an effect of a thin outline of the subject’s white clothing from the white background, thus the badly needed separation of the subject from the background.

We can do the same with black on black, only this time we’ll have at least two white cards on each side of the subject so the reflected light from the white will have the edge-building effect on the subject’s clothing.

When using these white and black cards, simply place them as parallel and as close as possible to your subject without entering the image frame. This method works great when you only have two cards, though the ideal method is four cards, two on each side and affixing them together to form a V-shaped wall with the V-point facing away from the subject. Ideally 4-foot by 8-foot foam-core boards work best and if you can find the type with black on one side and white on the other side, this is even more efficient for studio use.

Chimera Lighting also makes some great, portable fabric panels. These panels are best bought as a kit which consists of the panel’s frame and several fabrics including the black on side and white on the other side fabric, various scrims and even some diffusion silks. These kits are known as the high-definition production kits and are what I like to use on location. My favorites are the 48-inches by 48-inches model and the 42-inches by 72-inches.

Remembering the 90-Percent Rule maybe one of the most important fundamentals in photography you’ll apply to many things including metering and exposure, tone on tone photography and even on clothing selection which we’ll cover in the next part.

The 90-Percent Rule—Part Two—Tone on Tones