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Last week we examined the nature of
depth-of-field. Now let's take a look at how depth-of-field can
be applied practically and creatively.
Greater depth-of-field is an inherent trait of
shorter focal length lenses, the wide angles. For most prosumer
digital cameras, the widest end of a zoom lens is the equivalent
of around 35mm (not terribly wide but still endowed with great
depth-of-field). Wide angle attachments are also available for
digital cameras. I own a 24mm (equiv.) for my CP990 and have
used Nikon's fisheye attachment… talk about depth-of-field!
Digital photographers are at a slight
disadvantage in that our lenses do not have the small apertures
found in 35mm film lenses. For instance, my 990's smallest
aperture at its widest angle is f:7.0. Most 35mm wide angles
stop down to f:16 while f:22 is not uncommon.
The wide angle is supposedly a favorite for
landscape photography for its ability to capture a greater
expanse. While this is true, it also tends to make distant
objects appear smaller, often defeating the purpose of the
photo.
In a Utah desert, I saw this metallic-looking
butte just a hundred yards off the road. I hiked a few yards to
get closer and eliminate roadside clutter and came across this
little wild sunflower (I guess… botanists, please don't write)
about a foot high.
Using a 24mm lens, I set the camera to
Aperture-preferred and chose the smallest aperture. Then I
squatted to bring the flower higher in the foreground. Although
the butte is the point of focus, depth-of-field brought the
flower into sharp focus and completed my composition.
Of course, using a small aperture requires a
long shutter speed to obtain proper exposure. This can be very
useful in photographing water. My friend Dave Huss made this
shot of an Austin, Texas, waterfall using a Neutral Density
filter, a small aperture and an exposure of 1/2 second. The
result is a soft, gauzy waterfall blurred by the movement of the
water during the long exposure. This technique is terrific in a
deep woods setting, allowing water to become a plastic shape
around a stationary object such as a leaf on a rock in the
stream.
Here's a last example where depth-of-field
doesn't apply. This night shot of the Potomac River from the
heights of Georgetown would have received a proper exposure of
about 1 second in the Auto mode. By switching to
Aperture-preferred mode and its smallest aperture, the exposure
time lengthened to about 8 seconds.
This long exposure allowed light sources such as
automobile headlights and taillights to paint their trails on
the image. The crowning glory is the departure of a jet from
Reagan National Airport, completing an otherwise flat
composition. |