Light Modifiers

ferent levels of brightness and provides an appropriate shutter speed/aperture
combination to record these “averaged” tones at a value of 18 percent gray. Unfortunately,
unless your subject or scene actually consists of tones that average out
to 18 percent gray (and few do), using your camera’s meter will not provide an
accurate brightness rendition.
For example, if you are photographing a bride in a white dress, the reflectedlight
meter will see all the light tones from that dress and try to average it down
to 18 percent gray—producing an underexposure (the dress will record as gray).
Conversely, if you are photographing a groom in a black tuxedo, the reflectedlight
meter will see almost no light bouncing back from the fabric and try to average
it up to 18 percent gray—producing an overexposure (the tuxedo will
record as gray). This becomes tricky at best when both extremes (black tuxedo and
white dress) appear side by side in an image. To record accurate tones, you will
have to compensate via your exposure settings—using settings other than those
suggested by the meter.
Incident-Light Meters. A more accurate method is to measure the brightness of
a scene using an incident-light meter. Incident-light meters measure the light
falling on the subject—the actual light values in the scene, regardless of the subject
being photographed. In the bride and groom example, recording the light “falling
on” the subjects will ensure that you record the white dress as white and the black
tuxedo as black.
In my opinion, the most accurate rendition of the scene can be obtained using
a hand-held meter such as the Sekonic 758DR (photograph 1-11). Most handheld
meters have a white dome attached to the front that gives you a 180-degree
angle of view. Additional attachments could include a flat sphere that can replace
the dome for reflected-light readings of a scene. (For example, you might want to
use the flat sphere to take a reflected-light reading of a background to determine
its value relative to the subject brightness.) A hand-held meter is essential when
using a variety of light modifiers and light sources in a creative fashion that we’ll
discuss more later. The brightness of a scene will not only determine the exposure,
it will also set the mood—or “key”—of your image (see page 19).
Contrast. Contrast describes the difference in brightness between the highlight
and shadow areas of a photograph. This can be controlled by subject placement,
light placement, and the use of light modifying tools and techniques. Just as the
clouds in the sky control the relative contrast of the sun, you can actively control
the contrast within an image in the studio. The contrast in an image refers to the
difference between the rate of transition of the highlights and shadows in an
image. The contrast of an image can be controlled several ways. Through intentional
exposure manipulation, an image that is underexposed will have a lower
contrast than an image that is overexposed. The most common way to control
contrast is with the use of light modifiers, thus producing images that portray
hard or soft light.
Specularity vs. Diffusion. The size of your light source relative your subject
will determine the specularity and diffused light qualities of your image. This will
be determined both by the physical size of the source itself and its distance to the
22 THE DIGITAL PHOTOGRAPHER’S GUIDE TO LIGHT MODIFIERS
PHOTOGRAPH 1-11. Sekonic 758DR light
meter. Photo courtesy of Mac Group.