f/11 and half as much light as f/5.6. However, when we
talk about light ratios, each full stop is equal totwo units
of light. Each half stop is equal toone unitof light. This
is, by necessity, a suspension of disbelief, but it makes the
light ratio system explainable and repeatable.
In portrait lighting, the fill light is always calculated as
one unit of light, because it strikes both the highlight and
shadow sides of the face. The amount of light from the
main light, which strikes only the highlight side of the
face, is added to that number. For example, imagine you
are photographing a small child and the main light is one
stop greater than the fill light. These two lights are me-
tered independently and separately. The one unit of the
fill light (because it illuminates both the shadow and
highlight sides of the faces) is added to the two units of
the main light (which lights only the highlight side of the
face), indicating a 3:1 ratio.
Ratios for Children.You will most often see children
photographed with low to medium lighting ratios of 2:1
to 3.5:1.
A 2:1 ratio is the lowest lighting ratio you should em-
ploy. It shows only minimal roundness in the face. In a
2:1 lighting ratio the main and fill light sources are the
same intensity (one unit of light falls on the shadow and
highlight sides of the face from the fill light, while one
unit of light falls on the highlight side of the face from the
main light—1+1=2:1).
A 3:1 lighting ratio is produced when the main light
is one stop greater in intensity than the fill light (one unit
of light falls on both sides of the face from the fill light,
and two units of light fall on the highlight side of the face
from the main light—2+1=3:1). This ratio is the most
preferred for color and black & white because it will yield
an exposure with excellent shadow and highlight detail.34 CHILDREN’S PORTRAIT PHOTOGRAPHY HANDBOOK
Here, Stacy Bratton used her custom-
ary very large softbox off to the side,
but with no fill source. The effect is
dramatic lighting with a fairly strong
ratio of 3.5:1. She also used a small
backlight source to give some illumi-
nation to the painted backdrop.