Black and White Photography

as “2” (1/2 of a second), so it allows half as much light to reach the film. And
“250” (1/250) is twice as much time as “500” (1/500), so it allows in double
the light.
Each halving or doubling is called one stop. The half/double relationship is
not coincidental; remember that f-stop settings have exactly the same relationship.
You control exposure by balancing the combination of shutter speed and
f-stop to permit the correct amount of light to enter the camera.
Some shutters are mechanical, driven by gears and springs, and others are
electronic. Mechanical shutters can be set only for the speeds designated by the
shutter-speed dial; even if you try to set the shutter between two designated
speeds—say, 1/60 and 1/125—the camera will set one speed or the other. Some
electronic shutters function only at designated full shutter speeds, but almost
all provide intermediate choices in either half-stop increments, such as 1/90
(halfway between 1/60 and 1/125), or third-stop increments, such as 1/80 and
1/100 (between 1/60 and 1/125). Note that on these cameras, one click of the
control wheel is not necessarily a full shutter speed adjustment. If you are
trying to make a full, one-stop change, check the LCD panel to ensure that you
have not set a half- or third-stop setting by mistake.
One clear advantage of mechanical shutters is they don’t depend on batteries
to work. If you have a camera with an electronic shutter, it won’t work at all
if the batteries are exhausted. However, electronic shutters are more accurate
and generally quieter than mechanical shutters. And with half- or third-stop
settings they allow more precise exposure control.
Almost all cameras offer a “B” (bulb) setting and a few offer a “T” (time)
setting. Both permit the shutter to remain open for an indefinite period of time
for very long exposures, often called time exposures. These settings are especially
useful in dim lighting conditions, when adequate film exposure may
require shutter speeds ranging from a few seconds to as long as several minutes.
When set at “B,” the shutter remains open as long as you keep the shutter
button pressed down. When you release the button, the shutter closes. When
set at “T,” the shutter remains open from the time you initially press the button,
and then closes when you press the button a second time.
The shutter speed setting controls the appearance of a moving subject. Faster
shutter speeds stop (freeze) movement, but if the shutter is open for a longer
time, the moving subject may blur. Thus, you have the option of choosing a
shutter speed fast enough to stop motion or slow enough to create blur,
depending on the effect you’re looking for.
Most of the time, you will want to stop movement, and this generally requires
a fairly fast shutter speed. Just how fast depends to a large degree on

your subject. As a general rule, subjects that move quickly need the fastest shutter
speeds; subjects that move slowly—or don’t move at all, such as rocks and
buildings—need slower speeds. You may be able to freeze the motion of a
walking dog at 1/125, for example, but you may need 1/1000 or faster to stop
the motion of a galloping horse. Or you may use a setting slower than 1/60 or
1/125 to deliberately blur your subject; the slower the speed, the greater the
blurring effect. Note that at slow shutter speeds, blurry results also may be due
to camera shake.
The direction and distance of the moving subject can prove as important as
its speed. If the subject moves from side to side (left to right or right to left), its
image will cross the film faster than if it travels directly toward or away from
the camera. Therefore, you will need a faster shutter speed to freeze the movement
of the horizontally moving subject than for the one that travels directly
toward or away from you. (And you will need an in-between speed for subjects
moving diagonally toward or away from you.)
Furthermore, if your camera is close to your subject, movement appears
faster than if you are further away. Therefore, you will need a faster shutter
speed to freeze close moving subjects than you will for distant ones.
Subtle subject movement is yet another factor. Generally, landscape subjects
don’t require fast shutter speeds since they don’t appear to be in motion.
However, a strong wind can easily move grass, foliage, or tree branches. On