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## Lighting, Composition and Subject Lighting Part 5: How to Determine Phase Angle in the Field

by Roger N. Clark

The direction and quality of the light on the subject are the most important keys to image impact. The subtleties of phase angle cam make the difference in image impact. This article describes how to determine phase angle in the field.

The Lighting, Composition and Subject Series:

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Introduction

Understanding phase angle and its effects are keys to understanding light, the angle of light and image impact. See parts 1 - 4 (above) for information about phase angle.

Phase angle is the angle between the light source (e.g. the sun) and the viewer from the position of the subject. However, is is not always possible, or safe, to stand by the subject to do this estimate. This is not a problem with outdoor photography where the sun is illuminating the subject. Because the sun is relatively far away, the phase angle on the subject is the same as that at your camera. Thus, one can simply stand beside your camera facing toward the back of the camera and determine phase angle.

• place one arm parallel the the camera's optical axis.
• Point you other arm toward the sun.
• The angle between your two arms is the phase angle (see Figures 1 - 5).

In studying the images in Figures 1 - 5, note the shading on the brown jacket as well as in the vegetation. The effects discussed in Parts 3 and 4 are also seen in these images.

Figure 1. Low phase. Can you pick out the zero degree phase angle point? The answer is below.

Figure 2. About 20 degree phase angle.

Figure 3. About 30 degree phase angle.

Figure 4. About 90 degree phase angle.

Figure 5. About 160 degree phase angle.

Answer to Figure 1a: the zero degree phase point is at the center of the shadows of the camera near the right edge, below center.

Conclusions

Determining phase angle in the field is simple. After gaining some experience with this method, you'll probably be able to examine a subject and closely estimate the phase angle visually without having to do the above arm tricks.

A note about the sunglasses: the world really does look better through rose colored glasses!

If you find the information on this site useful, please support Clarkvision and make a donation (link below).

The Lighting, Composition and Subject Series:

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http://www.clarkvision.com/articles/lighting.part5/

First Published November 1, 2014
Last updated November 1, 2014.