Lighting & Composition People and Pets

About Lighting Ratios

Lighting ratios—they’re often misunderstood, and that’s unfortunate because, as you are about to see, there’s nothing that’s really complex about them. If you want to understand what lighting ratios are, all you have to do is to think of one word—“contrast.” That’s what they are about. Put simply, lighting ratios are nothing more than a numeric way of expressing how contrast-y the light you are using to make a photograph is. They are nothing more than a measure of how much difference there is between a scene’s brightest (highlight) and its darkest tones (shadows).

Take, for example, Figure 9. It’s a very “flat” portrait of my assistant, Mike. That’s to say that there’s almost no difference between the lightest and the darkest tones on his face. From that, we know that the main and fill lights I used were equally bright. If we were to translate that into “ratio speak,” we would say that I made this portrait using a 1:1 lighting ratio.


Figure 9. I used a 1:1 lighting ratio when I shot this picture of Mike. Notice how “flat” it is. That’s because the main and the fill light I used to make it were of the same

Now let’s move on to Figure 10. Notice how Mike’s face shows considerably more contrast in its lighting. This time there is a noticeable difference between this image’s lightest (left side) and darkest (right side) tones. That tells us that there was a considerable difference between the intensity, or brightness, of the main and the fill light that I used in making it.

lighting ratios

Figure 10. This time I used a 4:1 lighting ratio to shoot Mike. That means the main light I used to shoot this image was four times as bright as my fill light.

In fact, I did change my lighting when I made Figure 10. This time, instead of using main and fill lights of equal intensity, I boosted the brightness of my main light by two stops. This made the brightness of my main light four times as bright as my fill light. Shifting, once again, into “ratio speak,” we can say that I shot Figure 10 using a 4:1 lighting ratio.

So far, I’ve explained what lighting ratios are. That’s certainly a useful thing to know. But an equally important question is, “Of what importance to me are they in making my portraits?” The answers to that can vary. If you like to be very precise, and if you have a good light meter, you can control the lighting ratios you use in your portrait making with very great precision. Some photographers I know and respect highly like to work that way.

Personally, I generally prefer to take more of an “eyeball,” or instinctive, approach to lighting. I tend to like portraits that are a bit on the contrast-y side. To achieve them, I move my lights around until they produce the look I want on my subjects. When I’m there, I shoot. As our friend, widely respected photographer and author Fil Hunter, has said, “Get the main light right, then fill in as much as you like— actually works pretty well.”

Finally, let me inject a bit of very simple math into this discussion. If you want to find your way around in the wonderful world of lighting ratios, all you have to do is to divide or multiply by a factor of 2. It’s that simple.

For example, if you want to know the ratio for a portrait you made in which there is a three-stop difference between your main and your fill light, simply multiply 3 by 2. The answer is 6. Thus you have a 6:1 ratio.

If, on the other hand, you would like to know how many stops difference a 5:1 ratio represents, the process is equally simple. Just divide 5 by 2. The result is 2½. That means there’s a 2½ stop difference

Excerpted from FACES: Photography and the Art of Portraiture by Paul Fuqua and Steven Biver © 2010 Taylor & Francis Group All Rights Reserved

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