Fast lenses 123A shallow depth of fi eld takes the viewer’s eye right to the action of this steer-roping cowgirl. The background
is blurred, but with enough detail to set the scene and keep the fl avor of the event. © 2004 Barry Staver.
there’s a lot of action occurring, and we need to photograph it.
The extra stop of light provided by fast lenses is enough to freeze
the action, producing acceptable photographs. Another benefi t
of fast lenses is the shallow depth of fi eld when used at the
maximum apertures. After all, it makes no sense to have these
specialty pieces of glass if you’re stopping down to the mid-
range of f/4.5–f/8.0 or f/11.0 on a regular basis. Throwing the
background, foreground, or both out of focus is preferable in
many photographs, especially for portraiture, sports, and wed-
dings. The eye automatically goes to the in-focus part of the
image when the rest of the image is soft. The depth of fi eld with
these fast lenses, shot wide open, is measured in mere inches or
fractions of inches. Although this is a benefi t in general, it can
cause problems if you’re not careful. Let’s say you’re taking a
traditional head-and-shoulders portrait of two people. Even with
their heads close together, a photograph made with an f/1.2,
f/2.0, or even an f/2.8 aperture could render part of a face out of
focus. That’s cool in the world of fi ne art, but not acceptable for
traditional portraiture.
Another distinct and often overlooked benefi t to using fast
lenses: brighter images seen through the viewfi nder. Because
we’re working with these lenses primarily in low-light situa-
tions, a brighter image equals less-tired eyes, plus the ability to
see the subject better.