Understanding And Controlling Strobe Lighting; A Guide For Digital Photographers

The following is an excerpt from Understanding and Controlling Strobe Lighting: A Guide for Digital Photographers by John Siskin, published by Amherst Media (ISBN: 978-1-608952-42-7). John has been a Shutterbug contributor and we were glad to see him bring his knowledge on the topic of lighting to this new book.—Editor

Hard Or Soft Light?
In the past, most portraits were made using hard light. Photographers worked with large format cameras and slow film and a lot of light. Without a lot of light, portrait subjects would have had to sit still for a very long time. Many fine portraits, for instance, the old Hollywood studio portraits, were made with lots of hot lights.

(Top Left): The light on the right side of her face is twice as bright as the light on the other side, so we have a 2:1 ratio. (Top Right): Here we have a 3:1 ratio. You can see that there is a little more contrast. (Above): A 5:1 ratio looks pretty good in black & white.
All Photos 2011, John Siskin, All Rights Reserved

As we’ve learned, light sources that are large and close to the subject produce softer light than sources that are small and farther from the subject. As I discussed in chapter 3, there are many tools photographers can use to make a hard light source softer and more diffuse.

As seen in the diagram, the camera and fill light were positioned at the 12:00 position, and the main light was positioned at 2:00. This is a standard way to set up ratio lights.

Ratio Lighting
A light ratio is the numeric description of the difference in intensity between the highlight side (illuminated by the main light) of the subject and the shadow side (illuminated by fill light). The fill light is placed more or less directly in front of the subject and thus provides light over the whole face. The main light is positioned between 1:30 and 3:00 and illuminates just one side of the face.

(Top Left): This light produced by this single large light source is very soft. (Top Right): The lights are set to a 2:1 ratio, but you can’t see it in the face! (Above): In this image, the lights are set for a 5:1 ratio, but the lighting is even. Ratios just don’t mean much with large light sources.

The side of the face lit only by the fill light has a numeric value of 1 (e.g., one unit of light). If the main light provides the same amount of light as the fill, the bright side is said to have twice as much light as the fill side and has a numeric value of 2. The ratio in this setup, then, is 2:1.

Ratio lighting works with hard lights. In my career, I have witnessed other photographers trying to apply light ratios using soft lights. I try to discourage thinking in terms of ratios with large light sources, as the results don’t show a characteristic difference between the two sides of the face. Of course, if you use more modestly sized light sources or position your lights farther from your subject, the light will exhibit more of the characteristics of hard light.

This is the setup that I used for the shots with the large light sources. The lights were basically positioned like they were for the hard light setup, but the results are very different!