C O N T R O L L I N G
D E P T H O F
F I E L D
The topic of depth of field (DOF) tends to give the shakes to many beginning
photographers, but the concept is actually very simple. It is the range in a
scene, from near to far, that is in sharp focus. The ability to control how
much is in focus has an immense effect on your pictures. When shooting a
landscape, for example, you'll want as much of the photograph in sharp focus as
possible, so a significant depth of field is required. In other situations, as
in taking a portrait, a shallower area of sharp focus will isolate your subject
from distracting backgrounds.
Three things control how great the depth of field will be in a photograph:
lens focal length, aperture, and distance from the subject. Other things being
equal, shorter-focal-length lenses, smaller apertures, and greater
lens-to-subject distance all increase the range of sharp focus, while longer
lenses, wider apertures, and a shorter distance to your subject shrink depth of
field.
When you look through your lens, however, you will not be seeing what's
really sharp and what's not. With point-and-shoot cameras, this is because
you're not looking through the lens--you're looking through a separate
viewfinder. With SLRs, you're looking through the lens at its widest aperture;
it closes to a smaller f/stop only at the instant you press the shutter
button. This is a problem if you're using a medium telephoto lens to take a
portrait of Mom in gay Paree. As you look through the lens, it appears
that the traffic and crowds in the background are out of focus. But because you
have a small aperture set, when you get the picture back, zingo, Mom is lost in
all that junk behind her.
The solution? Many SLRs have a depth-of-field preview button; when you press
it, the lens briefly closes to the shooting aperture, showing you the real
depth of field. Be aware that when you press this button, the image in the
viewfinder will temporarily darken. If too much is in focus, simply open the
aperture, put on a longer lens, or move closer. Or all three. If too little is
sharp? Well, you can figure that out.
C A M E R A
H A N D L I N G
Optical and film quality are so good today that even the cheapest cameras
can make acceptably sharp pictures. Why, then, are "blurry" pictures
the chief complaint among casual photographers?
The answer is simple: You must hold the camera steady. More pictures have
been ruined by shaky hands than all the poor lenses in the world. Whether
you're using a point-and-shoot or an SLR, the best technique is to rest the
camera in the palm of one hand and squeeze the shutter button gently with your
free hand. Gently.
The effects of camera shake increase with telephoto lenses (or zooms set at
telephoto settings), as these lenses are heavier and magnify not just your
subject's size but any camera shake. Most automatic cameras are programmed to
pick a sufficiently fast shutter speed and have a warning beep (and/or a light
in the viewfinder) that lets you know when your speed's too slow. If you get a
warning, either switch to a higher shutter speed or, if that's not an option,
find something to rest the camera on--a fence post or porch rail, for example.
Another solution is to use a tripod or monopod (see Shooting Accessories),
which is something you might consider, especially if you're traveling by car
and have a place to stow it.
Z O O M
E F F E C T
In addition to offering you the marvelous convenience of being able to
change focal lengths quickly between pictures, zoom lenses enable you to create
a novel special effect by changing focal lengths during an exposure. The
result of this zoom effect is a relatively sharp central subject engulfed in a
radiant burst of light streaks. The effect works best with a strong color or
tonal contrast or with a brightly colored subject set against a dark
background.
With a slow-speed (ISO 64 or slower) film, take a meter reading of your
subject using your shutter-priority- (or manual-) exposure mode. The effect is
most pronounced when you zoom through the entire focal range, so choose a
relatively slow shutter speed--preferably 1/8 second or longer. To make the
exposure, simply press the shutter button with one hand and slide or twist the
zoom through its focal range with the other. Coordinating your two hands on the
two controls takes some practice, but the slower the shutter speed, the more
time you have to unravel the logistics.
Using a tripod is a necessity, because you're going to need both hands to
operate camera controls and because once you begin the exposure, the reflex
mirror of your SLR will be locked up, blocking your view of the subject. It's
also simpler to compose the picture if you zoom from the longest focal-length
setting (telephoto) to the widest (wide-angle); that way you know for sure what
will be in the center of your frame.
Once you are comfortable working with stationary objects in broad daylight,
try something a little more challenging, like a sports-action shot. The added
dynamics of the zoom streaks intensify the impression of speed and motion. Night
shots (see the photograph of the city overview) are also powerful--as you zoom,
each little droplet of light becomes a scintillating trail of color.
A U T O F O C U S
T E C H N I Q U E S
One ingredient of sharp images is focusing the camera carefully. Back in the
ancient days of photography, a decade or so ago, focusing a camera meant laboriously
twisting the lens barrel until the image in the viewfinder was in sharp focus.
Autofocus (AF) technology today has made focusing as painless as pressing a
button; still, to increase your percentage of sharp pictures, keep a few things
in mind before you press it.
All autofocus systems, for example, require that you place your subject at
the center of the viewfinder, because that's where the focusing sensors are.
What if you decide to get a little artistic by putting your subject, say, a tad
off-center? No problem; AF systems have a focus-lock feature (usually activated
by partially depressing the shutter button) that lets you focus with your
subject in the center, lock focus, then recompose to put it where you want it.
Most AF cameras offer two focusing modes: single-shot and continuous. If
your subject is one that sits still (like a landscape or a very good dog), the
single-shot mode is better, because it will not fire the shutter until it finds
sharp focus. If you're trying to snag a moving target (like a race horse or a
not-so-patient dog), switch to the continuous mode, and the camera will
continuously refocus until the instant of exposure. In this mode, however, the
shutter will fire whether or not your subject is sharp.
Most point-and-shoot cameras use an "active" AF system that
bounces an infrared light beam off subjects, while most SLR cameras use a
"passive" system that focuses by measuring subject contrast to
determine subject distance. The advantage of active systems is that you can use
them in virtual darkness as they provide their own focusing light; their
disadvantage is that they are not as precise.
Passive systems are more accurate but require a certain level of contrast to
focus and may have trouble focusing on subjects of low contrast, such as a
white wall or a foggy harbor, forcing you to resort to a manual-focus mode.
B L A C K - A N D - W H I T E
Though the idea of working in black-and-white may seem a tad old-fashioned,
reducing the world to a palette of grays has a number of creative benefits. By
wiping away the superficial veneer of color, black-and-white films unleash a
world of line, shape, texture, and form that color films often disguise.
Black-and-white pictures also have an inherently journalistic look, which
forces viewers to give more serious consideration to the content of your
images--an important point if you want to add social commentary to your travel
pictures.
Black-and-white films do not record the world in the same way that color
films--or our eyes--see it. While they are sensitive to all the colors of the
spectrum, they are more sensitive to some (particularly blue) and less so to
others (greens and reds). If you are photographing a red barn in a green field
with a blue sky, the sky will be very light, while the barn and grass will
record as much deeper shades of gray. Also, because the red and green
sensitivities of black-and-white film are similar, the barn and grass will
record as much the same tone.
If you own an SLR and a few colored filters, it's easy to manipulate the way
black-and-white films record different colors. Filters enable you to
reestablish a more natural-looking contrast by controlling how much light of
each particular color strikes the film. The basic rule to remember is this:
Filters lighten objects of their own color and darken opposites. A yellow
filter, for example, will lighten the tone of a yellow dress while slightly
darkening a blue hat. A red filter will cause a red barn to record as a much
lighter shade of gray but will make both green grasses and blue skies record
very dark.
One other advantage of shooting in black-and-white is that it's not very
complicated or expensive to get started in processing and printing your own
pictures at home--and create a whole new range of special effects.
M O T I O N
The idea in photographing most action subjects (see Sports) is to use
a shutter speed that's fast enough to stop any hint of motion. There are times,
though, when intentionally switching to a slow shutter speed and exaggerating
subject movement better interprets its true essence. A race horse frozen in
mid-stride is not nearly as expressive of action as one whose four legs are
tangled in a rhythmic blur.
One way to capture action in motion is by keeping the camera steady and
letting the movement write its own story across the frame. In photographing a
rush-hour crowd, for example, standing in one place and using a long exposure
will turn the onslaught into a swirling array of faceless forms. As with
stopping action, the actual shutter speed you use will depend on three factors:
the speed of your subject, its direction, and how close it is. As a starting
point, estimate the correct shutter speed for stopping action and then
experiment with shutter speeds at least two times slower; typically speeds in
the 1/30- to 1/4-second range are effective.
In the technique called panning, you use a slow shutter speed and move the
camera to follow your subject. The result is a relatively sharp subject
surrounded by a blurred or streaked background. With a moderately slow shutter
speed (1/60 or slower), focus on your subject (a skier, say) and gently press
the shutter as you pan with it. It helps if there's a good color contrast
between subject and background. Panning is one technique for which a
point-and-shoot has an advantage, because you can continue to see your subject
during the exposure. With an SLR, once you press the shutter, the reflex mirror
will block your view.
Occasionally you may be the one in motion--trying to shoot pictures
from a moving cable car, for example. In these situations stopping action (not
to mention camera-shake) is near impossible, and it's often better simply to go
with the flow, slow down the shutter speed, and let some blur into your
pictures.
E X P O S U R E
A N D
M E T E R I N G
M O D E S
Getting correct exposure with most simple auto-exposure cameras is easy:
press the shutter button and the camera does the rest. More technologically
evolved (i.e., expensive) cameras often provide a choice of several exposure
and metering modes. Having to maneuver through a labyrinth of optional modes
may seem somewhat antiautomatic at first, but in reality they enable you to
become the master of, rather than a slave to, automation.
Exposure modes. A choice of different exposure modes enables you to
manipulate the camera's selection of shutter speeds and apertures to match a particular
type of subject: you can tell it to pick a fast shutter speed because you're
photographing a race horse, for instance. Generally, the more costly the
camera, the more modes you'll have to choose from, but these are the most
common options:
In Program Mode, you accept the role of technological slave and the
camera selects both the shutter speed and the aperture for you. It is often
called the green mode because it's frequently marked by a green "P"
on the mode-selector dial. The camera will choose a shutter speed that is safe
enough for hand holding and an aperture that will provide a moderate amount of
depth of field. It's ideal for shooting relatively stationary subjects (like a
tall ship sitting at anchor) that don't require either a very fast (or slow)
shutter speed or excessive (or excessively shallow) depth of field.
In shutter-priority mode you choose the shutter speed and the camera
selects an appropriate corresponding aperture. If you want to blur the water
rushing over a waterfall, for example, you can select a very slow shutter speed
and the camera will choose the correct aperture. Conversely, if you want to
halt a bounding terrier in mid stride, you can pick a fast shutter speed and,
again, the camera will select an appropriate aperture.
The aperture priority mode, as you've no doubt guessed, lets you pick
the aperture, while the camera selects the matching shutter speed. This is the
mode to choose when you want to manipulate depth of field. For example, you
could set a small aperture for extensive depth of field (in a landscape, for
example) or a large one when you want to limit depth (as in a portrait).
Metering modes allow you to control what part of a scene the meter
will take its reading from--an extremely useful capability when it comes to
getting good exposure in difficult lighting situations.
Averaging meters, as their name implies, simply average all of the
bright and dark areas in a scene to provide an "average" exposure. If
the range of brights and darks in a scene is modest, averaging meters provide
good exposure. Problems arise when a scene contains particularly large areas of
either bright or dark subject matter (see Exposing for Light and
Dark Subjects), which can fool the metering system. Most averaging meters
overcome this handicap by also using a center-weighted design that gives added
emphasis to the center section of the viewfinder, which is, not coincidentally,
where most of us put the important subject matter. If you aim the center
section at this important part of your subject, excluding dark or bright areas,
the meter can calculate a more accurate setting.
Spot meters, a more sophisticated version of center-weighted meters,
take their readings from an even smaller section of the viewfinder--often just
a few degrees of the total view. Spot meters are an ideal solution in
situations where you want to meter a very small area of one tone against a
large area of brightness or shadow--a person's face surrounded by bright sky,
for example.
Matrix metering or evaluative systems, by far the most sophisticated
type of metering wizardry, are eerily accurate even in the most confounding
situations. They work by dividing the viewing area into a series of key zones
and taking separate readings from each area. This information is then fed into
a computer chip that has been programmed with hundreds of thousands of
potential lighting combinations; the meter then makes an educated guess at what
the important parts of your scene are and exposes accordingly.