Petersens PHOTOgraphic

Transcription

VOLUME 21 CREATE GREAT IMAGES WITH YOUR DIGITAL CAMERA
© George Schaub
photographic.com
Table Of Contents
PETERSEN’S PHOTOGRAPHIC DIGITAL PHOTOGRAPHY GUIDE VOL. 21
COLOR & LIGHT
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Introduction
Color And Light In Digital Photography
by George Schaub
Articles & Images by George Schaub
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Light And Your Photography
Some “Seeing” Exercises
The Range Of Light
Significant Values And Exposure Decisions
The Exposure Equation
Science Serving Art
Exposure Modes
The Two To Use
Metering Patterns
Reading And Defining Light
Photos © George Schaub
COLOR & LIGHT 3
COLOR & LIGHT
Introduction
Color And Light In Digital Photography
by George Schaub
ne of the main challenges of
photography is being able to make
photos that c apture what you see
b e f o r e you. In t h e v i s ual ar t s, a
painter’s vision evolves on the canvas;
for photographer s, that vision has
to be instantaneous, instinctive and informed with
technique. It might be a beautiful sunset, a vivid play
of color, a complex design of light and shadow or a
par ticular moment that speaks to you in a special
way. While instinct comes with practice and personal
experience, the path to attaining the desired image
is one that requires an under st anding of how to
“translate” that expressive moment from the external
world to an image recorded by the camera.
While today’s sof t ware programs allow 1-touch
solutions to that “problem”, the best way to develop
your photographic eye—and in the bargain have more
fun with your photography—is to take personal control
of matters when making the picture. Auto exposure,
algorithms and all of the rest of the benefits of digital
imaging are f ine, but can also separate you from
the photographic experience and the satisfaction of
mastering and applying light, exposure and color
controls.
You can point, shoot and walk away with a fair
degree of certainty that you’ll get something for your
small amount of effort, but I have always believed that
there’s more to photography than gathering snapshots.
As you master the control of light you will begin to
actually see differently and get a full appreciation of
how photography can enrich your life even when not
walking around with a camera in your hand.
L i ght i s always c hanging—n o 2 s u n s e t s have
ever been the same. But there are cer t ain ways
to characterize light that can come in handy when
photographing, as they c an guide you in making
choices about White Balance, exposure patterns and
modes. The aim here is to open your eyes to the
picture possibilities that different types of light afford.
It is also to recognize that although you might see the
light in one way the sensor may record it as something
quite different. Reconciling vision and image making
is what recognizing types of light is all about.
Given that ever y moment is unique (and light is
always par ticular to the time of day, weather and
envir onment) her e ar e just some of the ways to
characterize and make the best of the light at hand.
In photography, light is often defined by its source.
Natural light is light from the sun, be it direct rays or
reflected from objects. Yet daylight has many moods,
colors and angles, all of which define a sense of place
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(and often time) in an image.
Ambient light is the light that exists within the scene.
It can be natural or artificial, although most commonly
it refers to a low light level and can be used to describe
candlelight or window light in a dimly lit room. But the
term also describes the light that you want to record
faithfully, as it creates the ambiance (or mood) of the
scene.
When photographers talk about “available light”
they are generally referring to low or dim light. It can
be indoors or outdoors, and often requires the use of
high ISO settings, slow shutter speeds and/or wide
aperture settings to make a recording that will capture
the essence of the scene and all of its details. On the
other hand, “artificial” light is illumination provided by
a filament bulb, flash or fluorescent light.
The light is also defined by its character, and how it
affects and interacts with the scene. Hard light creates
strong shadows and contrast. It can be the light at
high altitudes unimpeded by haze or dust, the light
from an artificial source placed close to the subject
or any light that brings out the texture of a surface.
It can result from a “point source” of light—a very
defined and focused ray of light—and might come from
a burst from a flash or the direct, defining light of a
low winter sky.
Soft light can be any light diffused through curtains,
clouds or other translucent material. The diffusion
breaks up the direc t beams into a sof ter glow. It
can be the result of stronger light passing through
translucent material or through atmospheric diffusion,
like fog, falling snow or rain.
Light can also impart a colorcast (or influence of
color) onto a subject or scene. Warm light has a yellow/
amber glow, usually imparted from a candle, lamp or
from the low, slanting rays of the setting or rising
sun as it travels through the dust of the atmosphere
at a low angle to the ear th. A “neutral” colorcast
means there is no intentional or naturally occurring
colorcast over the image. Colors record as you see
or remember them. Blue or cold light can occur when
subjects are photographed in the shade, under an
overcast sky or when shooting at high altitude due to
an overabundance of UV.
Light is also defined by its direction, the point of
view of the photographer relative to the light source.
Backlight is when subjects fall in their own shadow
or when—with translucent objec t s like leaves—it
passes through those subjects. It occurs when the
photographer faces the light source, even at a slight
angle.
Rim light is a type of backlight, but it is used to
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© George Schaub
help create a halo (or an aura) around the subject. When working
with portraits it is a way to create a bright field of light around your
subject; when photographing landscapes it can take advantage of
diffraction—the bending of light around an edge—to bring creative
flare to an image.
Side, or directional light, refers to light that seems to break in
from the far edges of the frame. It can often yield the most dramatic
lighting, and is an excellent point of view to enhance the texture
of surfaces.
Over the shoulder light is when the light falls from behind, or
slightly to the side of, the photographer and is often the easiest light
in which to work. It is wonderful for bringing out all of the tonal and
brightness level potential within a scene.
Light creates mood with color but also with the general tonal range
it creates. In most scenes there is a mix of bright and dark, but in
some cases the range of light is more limited or displays a limited
spectrum of light or dark tonal values. Those are called “keys.”
High key refers to a scene dominated by bright values. It can be
ethereal or blazing with light. Generally there are few deep or large
shadows to define the forms, as the image is flooded with bright
light.
Low key means a composition without much contrast between
the lighter and darker subjects—often from shooting in the shade,
in low illumination, overcast or other diffused, low light conditions.
Even this summary cannot incorporate all of the wonderful aspects
of light available to photographers, and I am sure as you read this
your mind brought forth even more types of lighting conditions and
possibilities.
The aim of this “short course” is to get you thinking about light
and then simplify matters and get down to the core ideas of seeing
and mastering light and color. Once you put yourself in a frame
of mind about the perception of the light around you and practice
capturing it, then you can begin to play with light and expression
and understand what a joy this can bring.
While we will use some digital controls—including White Balance
sets—this path is one where many of the so-called advanced controls
like Scene modes and “art” filters are put aside. The idea is to gain
an appreciation of light and how you can record it, not one where
we mar vel at the cleverness of camera programmers. You can
accomplish all of this without needing an expensive camera; 90
percent of all cameras today have the features with which you can
apply the techniques covered here. Y
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COLOR & LIGHT 5
COLOR & LIGHT
Light And Your
Photography
Some “Seeing” Exercises
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n order to gain an under st anding of how
to use your metering system to get great
exposures it is important that you begin to
see with a “camera eye”. Before you get too
deep into this issue, take some time to walk
around outside each day. Like in this glowing
fall scene (#1) take a look around and notice how
the world is composed of levels of light and dark and
how surfaces and different colors reflect more or less
light. Observe how shadows form, how their depth is
influenced by the proximity of the subject that created
them and the brightness of the prevailing light. Look
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at how color creates mood and a sense of place. Look
at the shadows and how they define form and space
and help define context and movement in the frame.
Look at the brighter areas in the frame, as in this
interior shot (#2). Observe how the surfaces affect the
light and how the direction of the light has a profound
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effect on our perceptions. Find a scene where there
are many levels of brightness—as in this photo made
in a flea market in Santa Fe, New Mexico (#3)—and
see how light and dark cause some areas to come
forward, others to recede and how that interplay
creates dimensionality in the image. Frame a picture
that has a rhythm of light to dark and notice how
the composition of those elements create depth and
spatial relationships, as in this photo of a staircase
in Las Vegas, Nevada (#4). Shadows define form
and brighter light creates context. The interplay of
detail and silhouette can be a powerful compositional
technique.
Light and color also create texture—an almost
visceral presence in photographs. If you want to
understand texture and light just look up at a stormy
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sky (#5). The play of light and dark
define texture, which in turn creates
edges, scale and shape. If you are
near water, take special note of how
it reflects the light and how changing
your point of view can create “spectral
highlights” — the glint from water that
is texture formed by bright light and
deep shadow (#6) as in this photo
made along the Spree River in Berlin,
Germany. Squint a bit and blur forms.
Look at how color and light form a kind
of halo around certain places and things,
how they form geometric shapes of light
and color that are the building blocks
of composition, as in this arrangement
of light and massive forms of the San
Francisco de Asis Church in Ranchos de
Taos, New Mexico (#7).
Once you have obser ved your
“framed” scene, change your point of
view so that the sun strikes it from
a different angle. Walk to the side or
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from where you originally stood. You
may notice that every time you change
position the relationship of brightness
values also shifts. A pond is an excellent
subject for this study (#8) because you
can walk all around it and see it from
many different aspects, each with its
own character and quality of light.
A tree that was bright and lustrous
before has become a silhouette. A body
of water that sparkled with light is now
a dark mass. Leaves on a tree change
in the wind as they reflect the light.
These suggested seeing exercises
are an important part of understanding
how a photographic metering system
wor k s and how light is t r an s late d
from the real world onto an image.
The aim is to under stand how light
int e n s i t y i s o r d e r e d f r o m li ght t o
dark and how brightness values are
relative to your point of view. It is
the f ir s t s te p in s e e ing thr ough a
“camera eye” and gaining an instinct
about how brightness values are
translated to vibrant tonal values in
your photographs. It also is a way to
ef fectively shape our compositional
and point of view decisions.
The ease of use and automation of
today’s cameras should not relieve
u s o f “ s e e in g” an d un d e r s t a n din g
how all of this work s. No mat ter
how automated or sophisticated
t h e c am e r a mi ght b e, t h e way we
inte r pr e t light is what le ad s u s t o
making exciting, ef fective images of
the world around us. Y
COLOR & LIGHT 9
COLOR & LIGHT
The Range
Of Light
Significant Values And
Exposure Decisions
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hink about what you would have to do in
order to make a good sound recording
of a symphony or c he s tra. T her e ar e
bass (dark) and treble (bright) notes of
different timbre—levels of pitch produced
by different instruments—and highs and
lows produced by timpani and perhaps a piccolo. The
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range of the sound you could record depends upon the
dynamic range of the recording media—it’s “natural”
abilit y to r ecord a range of music al sounds—the
placement of the microphones and the way the levels
are set on the device.
Re c or ding light in photogr aphy is similar. T he
ability to capture the full range of light depends upon
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how the sensor can respond to light (its dynamic
range), the way the light is read (the placement of the
microphones) and the placement of those brightness
levels on the recording scale in the photographic
system (like setting levels on a recorder). The aim
is to get a range of light to recreate the experience
of “being there”. Sometimes this requires getting a
wide a range as possible, such as this photo of a low
flying cloud over a mesa (#1); other times it means
manipulating and even constricting that range for
creative ends, like in this monochrome version of
Jordan Pond in Acadia National Park (#2).
At times you might want to limit the tonal range
by c ompr e s sing tone s and value s, like using
under e xp osur e via spot meter ing te c hnique s to
intensif y the color, as in the photo of a hot spring
in Yellowstone, National Park (#3). There are other
times when you might want to create a visual mood
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by emphasizing the brighter tones, such as the photo
made in the dif fuse light of a greenhouse (#4) or
digging deep into the darker tones or shadows to bring
out detail, like in this photo of an antique store window
at night (#5). There are times when the lighting will
force your hand—but the image will be at trac tive
as is—such as the photo of a statue in a Hong Kong
temple where direct sunlight struck the figure which
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drove all around it into deep shadow (#6).
T hat inter pr etive power is an option with any
photograph you make. It can be done when you make
the exposure and also in image processing. (Note that
we will stick with the recording side for this issue
because we recently did an issue on image processing.)
Photographic exposures “flex” to match the subject,
scene and mood you want to impart. The tools used
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for this flexibility include the sensor’s sensitivity (the
ISO), the aperture and shutter speed settings and
how you make light readings. We’ll cover all of those
tools and techniques later in this issue. The point is
that it is a “closed system” in the sense that certain
rules apply. While each scene and image may have a
different exposure, each one sits somewhere within
the borders defined by light and composition and how
you control each through exposure.
Significant Values
If you expose in a way that does not c aptur e
t he s c e ne pr o p e r ly it i s e it he r ove r e xp o s e d o r
underexposed. Overexposure means that too much
light has struck the sensor to properly record the
scene. This may cause brighter areas (highlights)
to lose detail. These Columbine blossoms have a
har sh look (#7) and all of the beautiful tex ture
of the flowers is lost because the light was read
from the darker background, “pushing” the brighter
a r e a s i n t o ove r e x p o s u r e. B a s i n g e x p o s u r e o n
the f lower s themselves (#8) and applying some
exposur e compens ation solve s this dilemma. If
we underexpose, not enough light has struck the
sensor and causes lost shadow detail and poor color
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rendition. This fall scene shows what you lose when
you do not expose properly on the underexposure side
(#9). When exposed properly all of the subtle beauty
that was available in the moment is revealed (#10).
When you look at a scene you should think about
what the “significant” values might be in both the
brighter and darker areas of the frame. That decision
will guide you in how you expose the image—how
you make readings and what might result. What’s
important in this sunset scene (#11)? Is it the details
in the trees or the brilliant colors in the western sky?
Is it necessar y to be able to distinguish details in
the open areas of this snow-covered pond and the
bark of the distant trees (#12) or is the image more
about patterns and forms? The point is that exposure
decisions should follow how your eye “sees” the scene
and how you want to interpret it. Knowing what’s
significant to you in the image will lead you in the
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right direction.
The range of light you decide to record includes
everything you see in your mind’s eye when you make
the picture. There are limits to what you can record,
but understanding significant shadow and highlight and
how they play a role in your interpretation is what the
combination of light and composition creates.
This is all well and good, but how do you translate
this way of seeing into an exposure that delivers what
you want? That ’s where master y of the exposure
metering comes into play, and that is the subject of
this issue. But in the somewhat technical discussion in
the next chapter that follows, keep in mind that it all
loops back to first seeing and appreciating light and
then understanding how it fits within the camera’s
recording capabilities. We’ll start that exploration by
concentrating on the elements of an exposure system
and how to harness them for your creative work. Y
The Exposure
Equation
Science Serving Art
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n this chapter we’ll look at the elements in
a camera’s exposure system and how they
are best put to use. You may be surprised
at the simplicity of what is actually a ver y
technologic ally sophistic ated system.
Digital cameras of fer a ver y wide variet y
of sometimes confusing options. But once you have
a basic understanding of how an exposure system
functions you can cut through all of that chatter and
get to the heart of how to work with it to make great
images. Following this discussion you’ll learn the tools
I
© George Schaub
that I consider most important, and those I consider
least advantageous, for light and exposure mastery.
Quantity & Quality
When photographers consider light, they deal with
both the measurable quantity of light and the quality
of that light. This “duality” is inevitably encountered
in the study and appreciation of photography, but
essentially it is how science and artistic expression
work together. In this photo made in Berlin (#1)
the quantity of the light is expressed in the darker
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© George Schaub
and lighter areas of the scene, a balance struck by
measuring and applying exposure settings. The quality
of the light is of greater impor tance, with the late
af ternoon sun bringing a sense of time and place
and defining the interplay of light and shadow. But
without applying a certain exposure, one that allows
for sharpness near to far and that also allows for
details within the darker areas of the scene, the quality
of the light would not come through.
On a pr ac tic al level, light mus t be measur e d,
controlled and channeled to “fit” within a photographic
system. The instrument of this transaction is the light
metering system in your camera. With a seemingly
uncanny ability it translates light energy (photons)
into electrical signals that are then turned into binary
code that can be read by a computer and monitor to
“recreate” the image on the screen.
The light meter in the camera translates light energy
into specif ic light controlling fac tor s that have a
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profound effect on how you interpret the scene—an
opening in the lens (the aper ture) and the shutter
speed (how much time elapses as you record it). In
this close-up (#2) decisions about where the light is
measured and the aper ture used create both vivid
color and the way the foreground blossom stands in
relief from the slightly softer background.
Another par t of the “equation of exposure”—or
balancing the light in the scene with the ability of the
camera to record it successfully—is the amazing ability
of the sensor to be made more or less sensitive to
light. This is accomplished by changing ISO settings,
which in today’s cameras allow us to make better
photographs in dimmer light than ever before. This
candid portrait of an elegant fortuneteller in a Hong
Kong temple (#3) could only be captured by raising the
ISO to 800. This allowed me to work handheld with a
telephoto lens in dim light.
With that, here are impor tant exposure
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considerations to keep in mind as you go deeper into
your photographic adventures. It is a bit technical,
so please bear with me, but I promise it will become
evident how it all works as we go through this issue.
Exposure Factors
An exposur e system work s with these fac tor s:
the brightness of the scene, the light sensitivity of
the sensor and the camera and lens controls that
determine how much light reaches the sensor—the
aperture and shutter speed settings. They all work
together. Think of it as a balancing act; on one hand
you have the light in the scene provided by nature and
on the other you have light controls you can change in
the camera to adapt to and enhance that light.
Exposure Value (EV)
Exposure Value (EV) is an abstraction—as are all
systems of measurement—that is at the hear t of
photographic exposure. I feel obliged to include an
explanation of it because it is so often referred to in
camera instruction books and is always working “in
the background” in every exposure you make.
EV is an expression of light levels in both the scene
before you and the camera exposure settings you
use to record it. It is a measure of the overall light
in a scene—and even par ts of the scene—such as
dif ferences in bright and dark par ts of the scene,
referred to as shadow and highlight. In this photo
of a building exterior (#4) there are a wide variety
of light and dark values and deep shadows. Each
level of brightness can be expressed as an EV. For
example, the reflective area could be EV15 and the
deep shadows EV6. This gives us a sense of the scale
(or range) of brightness in the frame. But EV is also
an expression of the exposure setting in the camera
system used to capture this range, a combination of the
amount of exposure allowed by a certain combination
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of aperture, shutter speed and ISO settings. In this
case the exposure was at EV14 (or f/11) at 1/125 sec at
ISO 100. The use of EV creates a “common ground” of
light measurement in both the scene and the camera.
EV, Camera & Lens Controls
Let’s break down the component parts of EV in terms
of both how bright the scene is and how it is translated
by an exposure system in a camera. We’ll start with
camera controls. Every whole number change in EV
represents a change of 1 stop of light (or a halving or
doubling of the amount of exposure). A 1EV change
in shutter speed means a faster or slower shutter
speed, going from 1/60 sec to 1/30 sec (+1EV). A
-3EV change would be from 1/30 sec to 1/250 sec.
It’s a minus value because the faster shutter speed
lets in less light. The camera reads the light in the
scene but translates it for you to aperture and shutter
speed settings, which you then “juggle” to get the
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effect you want.
In this scene of a street fair in Madrid (#5) the light
level was EV11, which I could then translate into a
combination of aperture and shutter speed. I never
saw the EV reading, just the settings as translated
by the camera. I chose f/8 at 1/30 sec to bring the
entire play of people, objects and reflections into
focus. (Note: If you want to see how EV light readings
translate to various combinations of aper ture and
shutter speed Google EV and choose the Wikipedia
link.) For this rodeo action in Wyoming (#6) the EV
scene value was EV14, and I selected f/4 at 1/1000 sec
to catch the action. Again, the light metering system
“read” EV14 and translated that scene light level to
aperture and shutter speed settings.
EV can also be used to express changes in aperture
settings, where +1EV might represent a change from
f/8 to f/5.6 or—more radically—from f/4 to f/16 (-4EV).
The change from f/8 to f/5.6 is +1EV because more
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light comes through; the change from f/4 to f/16
constricts the light coming through by -4EV. Note
that if you change +1EV in both aperture and shutter
speed you are actually changing the exposure by +2EV,
so each camera control affects light in and of itself.
The EV as read here (with the reading made from the
bright graffiti wall) was EV16 (#7), and I chose an
exposure of f/16 at 1/125 sec to keep the image sharp
from foreground to background.
Underlying the E V equation is the ISO, or light
sensitivity of the sensor. Going from ISO 100 to ISO
200 changes the sensitivity by +1EV and boosts the
light sensitivity of the sensor by 1 stop. Say you have
an exposure of f/8 at 1/125 sec and want a faster
shutter speed. Raising the ISO 1 step (or +1EV) can
yield an exposure of f/8 at 1/250 sec.
The shift is more dramatic when moving from ISO
100 to ISO 1600, a +4E V change that raises the
sensitivit y to the point where the exposure could
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be f/8 at 1/2000 sec—something to keep in mind
when shooting sports or where you want to freeze
the action. The day was ver y overcast and stormy
when I was photographing geysers in Yellowstone
National Park, and the light level was EV9 (#8). I
wanted to shoot at f/8 to get the foreground trees
and background sharp, but at ISO 100 this yielded a
shutter speed of 1/8 sec. I didn’t have a tripod with
me so I raised the ISO to 800, a gain of +3EV. This
allowed me to shoot at a steadier 1/60 sec (1/8 to 1/15
to 1/30 to 1/60 = +3EV).
Shif ting ISO slides the scale of light sensitivity,
and is a very useful tool when working in low light or
when you require fast shutter speeds and/or narrower
apertures for deeper depth-of-field. (The shift can also
be used to keep the shutter speed constant and work
with a narrower aperture.) Those with photographic
experience work with this system all the time without
thinking too much about it. If it seems confusing to
you now, trust me that it will become more second
nature than the math class it seems to be.
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EV & Exposure
The trick of all this is; the scene may have many EVs
throughout, while the camera exposure can only be
made at one EV at a time (except for special cases like
HDR exposure, which relies on multiple shots of the
same scene at different EVs and then combining them
later in software). How do we decide what camera
set tings to use? How do we select the brightness
value that will get us the best image? In some cases
it will be by choosing one EV and working around it;
in others we let the camera average the EVs for us. As
shown in the examples described above, the metering
system reads light levels and then shows them to you
in terms of aperture and shutter speed settings. You
then choose the combination that fits your needs.
EV Scenarios
To give you an idea of how the scale of EVs work in
nature, here are a few scenarios and their EV exposure
levels, with possible exposure settings that will handle
them. These assume that you have set your ISO at
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100. These are not meant to be hard and fast exposure
rules, but are cited as examples of typical settings.
Alongside the EV numbers I’ll show you the actual
exposure chosen for the scene.
Snow In Sunlight (#9): EV16 (f/22, 1/125 sec). A
Narrow aperture chosen to get sharpness from near
to infinity.
Sunny Day (#10): EV15 (f/16 at 1/125 sec). This is
a good combination of aperture and shutter speed to
capture these ascending balloons.
Overcast, Open Shade (#11): EV12 (f/8 at 1/60 sec).
The door of the abandoned bar was shaded by the
overhanging porch.
Cityscape At Night (#12): EV6 (f/4 at 1/60 sec). EV6
at ISO 100 would have yielded an exposure of f/4 at
¼ sec—way too slow to ensure a steady shot. I raised
the ISO to 1600, which gave me a +4EV gain, which I
“spent” on shutter speed to gain a respectable 1/60
sec exposure.
Equivalent Exposure & Image Effects
A s you might have sur mis e d f r om what we’ve
covered, exposure controls in the camera are quite
flexible and you can shif t around the variables as
needed. The light in the each scene is a “constant” that
is “solved” by the equation of the in-camera exposure
control variables.
One of the most impor tant concepts in creative
c amer a c ontr ol is what is c alle d an “e quivale nt
exposure”. You might need a faster shutter speed or
a narrower aperture to gain a certain “effect” in your
image—by changing the sharpness depth or increasing
the shutter speed. Equivalent exposures allow you
to change one or both of these parameters without
affecting the overall exposure, or scene EV. And, if
you need to work with a narrower aperture or a faster
shutter speed, you can always raise the ISO to increase
the sensor’s sensitivity to the light levels at hand.
If you decide to change the shut ter speed from
1/30 sec to 1/250 sec to freeze the action (-3EV) as
long as you change the aperture +3EV in the opposite
direction from f/16 to f/5.6, the same amount of light
gets through. This balancing act is what allows for
different image effects with the same exposure. In the
system for exposure we’ll describe, you don’t have to
do this yourself—the camera’s exposure system does
it automatically for you. But it’s good to know what’s
occurring when it does and what you gain and lose
with each decision you make.
Here’s an example of an equivalent exposure scale.
(Note that the ISO remains constant in this scenario.)
The changes here can be used to gain a faster shutter
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or to shift the aperture to affect sharpness near to
far, known as a depth-of-field effect. These sets gain
you the same amount of exposure.
F/16 at 1/125 sec
f/11 at 1/250 sec
f/8 at 1/500 sec
f/5.6 at 1/1000 sec
Understanding how this works will allow you to have
expressive control over your photographs.
In the next chapter we’ll quickly review exposure
factors and then move right into exposure modes, the
settings you use to “tell” the camera how to use the light
information it gathers. This is where all the background
information comes into play; as you work with it you’ll
quickly understand how this elegant system gives you
complete creative control over your images. Y
Takeaways: Balancing Exposure Factors
This chapter has a lot to digest—but as you read through this issue and get a bit more familiar with your
camera controls—all this will become second nature. Here are some key elements we’ve covered.
Exposure is a balance between a number of factors both inside (the settings) and outside the camera
(the scene brightness). Both of these can be expressed as an EV value.
The ISO is the foundation of light sensitivity in a camera metering system. If you change the ISO, then
either the aperture or the shutter speed settings for the exposure of the scene will change.
Aperture and shutter speed changes are ways to alter image effects in certain scene EVs. In previous
photographic parlance the changes that halved or doubled the light for exposure were refereed to as +/1 stop. Similarly, a change in 1EV indicates an increase or decrease of exposure that doubles or halves
the amount of light of the exposure. If the exposure changes from 1/250 to 1/125 sec, you have a change
of +1EV. If it changes from f/5.6 to f/8, then half the amount of light reaches the sensor, and then it’s a
-1EV change.
Overall exposure does not change if both the aperture and the shutter speed change in opposite directions
of the same EV values. If an exposure changes from 1/125 sec at f/8 to 1/500 sec and f/4, the same
amount of light gets through. What changes is the way action is expressed (with 1/500 sec freezing the
action more than 1/125 sec) and the range of focus (f/4 yielding less range of sharpness than f/8). The
juggling of these numbers is what allows for different image effects with the same overall exposure. In
other words, the light level does not (always) dictate creative effects; it is how you use the aperture and
shutter speed settings within a certain light level that does.
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Exposure
Modes
The Two To Use
1
ow that we’ve dis c u s s e d E Vs—the
backbone and terminology used to
def ine the levels of brightness in a
scene and the camera exposure—let’s
review the tools in your camera and
lens used to manipulate light and then
look at exposure modes, how you tell the camera to
use the light in creative ways.
N
2
Sensor Sensitivity: ISO Speed
You set the ISO in your camera according to the light
levels in which you are working. ISO represents the
relative sensitivity to light of the sensor. Higher ISO
numbers correspond to more sensitivity to light; they
are usually expressed in steps that represent twice as
much or half as much light sensitivity. For example, an
ISO 200 setting is twice as light sensitive as an ISO
100 setting and half as sensitive as ISO 400.
You can shoot handheld (without a tripod) in dimmer
light without using flash when working with higher ISO
settings, such as this night scene of Hong Kong (#1)
made with an exposure of f/2.8 at 1/60 sec with an
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Today’s cameras have sophisticated
noise reduction filters that yield
surprisingly good results even at
high ISO’s, like ISO 25600.
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3A
ISO of 1600. This boost is accomplished by applying
an extra electrical charge to the sensor, but if you go
too high you’ll start to see “noise” from that boost in
your image, as you can see in this detail of a an ISO
1000 shot made with a digital camera from just a few
years ago (#2).
Today’s cameras have sophisticated “noise reduction”
programs, but there are limits, so keep in mind that
there is often a boundary between high ISO and image
quality falloff. An extreme setting of ISO 25600 (#3)
even on a fairly modern camera with sophisticated
noise reduction software still can get noisy, as shown
in this ver y small detail from a photo made in a
museum interior. At an 8.5x11”, a non-cropped print
is acceptable and even quite impressive (#3A), so it
shouldn’t stop you from exploring the possibilities of
working in low light with high ISO settings.
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Aperture
You set the aperture of the lens from controls within
your camera or (with select lenses) on the barrel of the
lens itself. When the aperture is opened wider, more
light comes in and when it is narrower, less light comes
in. Think of it as a physical control on the amount of
light that can pass. The aperture number increases as
the aperture itself narrows (f/4–f/16). This might seem
counter-intuitive, but these are fractions and a value
of f/4 (or ¼) is greater than f/16 (or 1/16.)
But changing the aperture also has an optical effect:
it changes how the light at various distances from the
camera can focus onto the sensor. Because a narrower
opening allows light in at a narrower angle the light
rays tend to focus more tightly together and appear
sharper. When the lens aperture is open wider the
fall of light onto the sensor from different distances
4
Changing the aperture
does more than change the
amount of light coming
through the lens. It also can
have a profound effect on
what’s sharp and unsharp
in the image.
is more diver se, from dif ferent angles, and some
areas seem “softer,” or un-sharp. A narrow opening
like f/16 will give you more foreground-to-background
sharpness—as in this photo of the World Trade Center
Memorial reflecting pool taken with f/16 with a wideangle lens (#4)—than if you have the lens set at f/4.
The depth of field on this photo of pussy willow stalks
made in a greenhouse is very shallow due to working
close with a 200mm lens (#5). It’s pretty magical and
is one of the most creative tools in photography.
Shutter Speed
This setting controls the amount of time light is
allowed to strike the sensor. Shutter speeds in digital
cameras can range from seconds to thousandths of
a second. Faster shutter speeds let in less light but
also catch shorter cuts of continuous motion, as in this
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photo of a pickup basketball game shot at 1/1000 sec
(#6). Slower shutter speeds allow in more light and
record longer cuts of action, as can be seen in this
photo of a flowing stream recorded at 1/8 sec (#7). If
you photograph with a very slow shutter speed, such
as this shot of a spinning carnival ride (#8) made with
a 1 sec exposure, objects in motion can meld and
create some interesting abstractions.
Tip: Think of the shutter speed as a knife that cuts
slices of time from its continuous arc. A faster speed
cuts thinner slices of time. This is another key creative
control in photography.
Shutter speed can also have a profound effect on
the steadiness of a picture. Slow speeds may cause
something called camera shake, resulting in a blurred
picture because the photographer was not able to
hold the camera steady during exposure. Some digital
cameras will warn you with a beep or light indicator
when this might occur, usually at shut ter speeds
of 1/30 sec or slower. If you use a long telephoto
zoom lens the camera shake speed might show up
even at 1/125 sec. To maintain a steady hand on this
200mm photo of Jackson Square in New Orleans (#9)
I exposed at 1/250 sec, and later converted the image
to black and white.
One of the real advances in lenses (and sometimes
within the camera body itself) is the incorporation
of “image stabilization” that will help you maintain
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a steady shot even at fairly low shutter speeds. It
is a highly recommended feature to look for when
buying a lens. The low light of this interior photo of
the cathedral in Cologne, Germany (#10) made for a
slow shutter speed even at a wide open aperture (f/4)
so to get a steady shot at 1/30 sec I worked with an
image stabilized lens.
Auto ISO
A new wrinkle in exposure control is Auto ISO. In this
mode you can have the camera determine the proper
ISO for the light levels in which you are working.
You can limit just how high you want the ISO to be
set at—for example, ISO 1600. You can also indicate
which shutter speed you want as a minimum—1/60
sec or even 1/250 sec or more. This comes in very
handy when you don’t want to guess at the ISO each
time you shoot and is a very convenient way to shoot
action subjects.
When photographing a hockey game, one of the
fastest sports there is, I knew I wanted a minimum of
1/500 sec shutter speed to catch the action, so rather
than guess at the ISO I set that parameter and the
exposure system chose an ISO of 4000 for me (#11).
Exposure Modes
Exposure modes are used to “tell” the camera how to
treat the light in order to attain various image effects.
While cameras today offer numerous modes we’re going
to slim it down to two—with another option thrown in for
good measure. My feeling is that by selecting exposure
modes it allows for your creative input and control in
each shot, plus you can have a more truly satisfying
experience in your photographic work.
Exposure modes use the automatic exposure system
in your camera and all the sophisticated metering
technology it affords. But this does not mean that you
have surrendered control of making personal exposure
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decisions by doing so. It does mean that you make
decisions about image effects before you make the
photo—whether to emphasize depth-of-field or how
motion is depicted in your photos. In some cases, by
using the ISO to raise or lower the sensor sensitivity,
you may be able to control both effects as you wish.
Choosing an E xposur e mode def ine s how your
c amera automatic ally balances the light r eading
between the aperture and the shutter speed settings.
For example, in this photo of a weathered tree on
the rim of the Rio Grande rift (#12) I chose Aperture
Priority and a setting of f/16 to get sharpness from
near to the mount ains in the dis t anc e, and the
exposure system chose a shutter speed of 1/250 sec
for me. Exposure modes are a creative choice that
informs the camera system what you want it to do
with the light information it receives.
You set the Exposure mode either with a dial on the
camera body or via the LCD menu, depending on the
of the model camera you use. But before we get into
the two modes I recommend you use (and mostly limit
your work to) I feel bound to say a few words about
Scene or so-called “Art Filter” modes.
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Scene Modes
Camera makers have the ability to combine various
picture interpretations and image manipulations at
the touch of a button or the turn of a dial. However,
being preset programs, they are fairly narrow in
their interpretation. And while some recent models
allow you to record an image in both their special
effect and “straight” recording look, most lock in the
interpretation in the recorded image. While some
can be fun and attractive, such as this “glow” ar t
effect on this iris (#13) you are in a sense stuck with
that interpretation on your original image. If you
shot it straight you can easily add that effect later
in software.
Scene modes are a bit less restric tive, but the
problem is they interpret the scene or subject for
you rather than you taking full creative control of the
effects you want. A common Scene mode is “Portrait.”
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14
Aperture Priority
T his is one of the t wo exposur e mode s that I
r ecommend that you get to know well. Aper tur e
Priority mode is usually indicated by “Av” on your
camera’s control dial. (Note that some makers label
this as “A”, which confuses it with a fully Auto mode,
which you certainly do not want to use. So check your
instruction book to differentiate between the Full Auto
and the Aperture Priority settings.)
As mentioned, the variable opening in the lens—the
aperture—performs two major functions. It controls
the amount of light coming through the lens plus
af fects how that light is focused onto the sensor.
But the c hief r eason for using Aper tur e Pr ior it y
(the priorit y par t simply means that the aper ture
set ting and it s ef fe c t is mos t impor t ant in your
picture consideration) is to control what is sharp and
un-sharp in your picture, known in photo parlance
as the depth-of-field. In Aperture Priority mode, you
set the aperture opening and the exposure system
automatically sets the shutter speed for the correct
exposure.
Depth-Of-Field
15
When you set Portrait mode the system assumes that
you want to have your subject stand out from the
background, so it favors a faster shutter speed and
wider aperture. This has the effect of throwing the
background out of focus. You may want this—or you
may not. It also “softens” the image slightly with a
flattering if slight blur, and in some programs even
adds a “warmer” or slightly yellow color cast to the
process. It may work for some portraits, but certainly
not for all.
In short, Scene modes impose a certain set of visual
aesthetics on what programmers consider the ideal
rendition of a par ticular t ype of subjec t. It ’s f ine
for point and shoot photographers but I discourage
its use because it takes away your ability to make
those decisions yourself. All in all I think they confuse
mat ter s more than necessar y and cer tainly don’t
contribute to your engagement in the photographic
process. By all means test them out, but do so more
out of curiosity than relying on them to be the source
of your creativity.
This brings up the topic of depth-of-field, a term that
defines that very sharpness/un-sharpness balance.
While the aperture setting has a profound effect on
depth-of-field (DOF), two other factors also contribute.
One is the camera to subject distance (the subject in
the frame you want to have sharp) and the other is
the focal length of the lens you’re using. In this photo
of a large drif twood tree taken on Jekyll Island in
Georgia (#14), I chose a 24mm lens and focused on the
lower left portion of the tree and stood about 4 feet
away, and at f/22 I achieved sharpness throughout the
frame. To get this painterly effect (#15) I stood back
with a 200mm lens and chose f/4 for the aperture—the
exposure system chose 1/500 sec and I got just the
background effect I wanted.
Some Live View models will show the depth-of-field
results as you make the settings right on the monitor
or electronic viewfinder before you make the photo.
Other D-SLR cameras will of fer a “depth-of-f ield”
preview button that will show you the effects right in
the viewfinder. Both visual aids can be invaluable in
Depth-Of-Field “Rules”
Here are the rules of depth-of-field control.
To get the deepe s t depth-of-f ield (to at t ain
sharpness as much as possible from the main, or
foreground, subject to far away):
1. Use a narrow aperture.
2. Use a wide-angle lens.
3. Do not shoot too close to your main subject.
To get the shallowest depth-of-field:
1. Use a wide aperture.
2. Use a telephoto lens.
3. Get close to your prime subject in the frame.
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your work. (Note: If your playback screen
is small the dif fer ence s will not be as
obvious as when viewing on a larger LCD
or monitor.)
Te c h Tip: Depth-of-f ield also c ome s
forward a bit from the subject you focus
upon as you narrow the aper ture. This
can be useful later on, when working with
macro (close-up) photography or even when
photographing large gr oups of people,
but for now we’ll concentrate on the near
subject to background sharpness effect.
One interesting depth-of-field trick is to
make the foreground obstructions “vanish”
through un-sharpness. This can work with
fencing or other thin obstructions, such as
in these photos of a merry-go-round roped
off for the season. Both photos were made
with the focus on the foreground horse, but
the one showing the rope was shot with an
aperture of f/14 (#16) and the other was
exposed at f/1.4 (#17). The un-sharpness
pretty much made the rope disappear and
softened the background in the bargain.
Once you get into creating background
effects it’s hard not to use them for every
subject and scene. It’s a very exciting and
creative control.
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Shutter Priority
Shutter Priority mode is our next key
Exposure mode. Indicated as “Tv” (for “time
value”) or “S” on the control dial, you choose
this mode to prioritize the shutter speed and
the automatic exposure system will make
an aperture selection for you. In this photo
made in the NYC subway (#18) I wanted the
sense of motion in the arriving train with the
remainder of the scene stable. I braced the
camera against a pillar and set the shutter
speed to 1/10 sec and the exposure system
chose an aperture of f/2.8 (ISO 100).
Shutter Priority is appropriate when you
want to def ine how motion is depic ted;
faster shutter speeds freeze the motion
while slower speeds blur it. It’s your choice
as to what works best for the scene.
You also use Shutter Priority mode to
set a higher shutter speed when using a
telephoto lens to help reduce shake. This
photo of a harbor at twilight was made with
a focal length of 150mm from a distant pier
(#19). I knew I needed a shutter speed of
at least 1/150-200 sec to have any chance
of a steady shot, so I set that in Shutter
Priority mode. The widest aperture on my
lens was f/4.5 and the camera indicated an
underexposure warning because of the low
light in the scene. My only out was raising
the ISO until f/4.5 did the trick, which in
this case was ISO 1200. The same
went for this photo of rush hour at
New York’s Grand Central Station,
where I had to go as high as ISO
6400 to get a steady shot (#20).
You can also use Shutter Priority
with a slow shutter speed to use
a te c hnique k nown as panning
(#21), a fun technique that can
freeze a subject in motion while
creating a blur of the background.
T h i s p h o t o w a s m a d e a t 1 /14
sec and the camera was moved
horizontally along with the motion
of the speeding night tram.
Creative blur—where part of the
scene is sharp and the motion of
a subject through it is un-sharp—
make s f or a vis ually ar r e s ting
scene that only a photograph (or
a painting) can reveal.
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Leeway In Priority
Exposure Modes
As you work in these Exposure
modes you will begin to see the
limitations of each. While we’ve
discussed the problems with slow
shutter speeds and camera shake,
there are more subtle problems
t hat might o c c ur, r eve al e d by
consideration of the range of EV
changes available in both modes.
A s we s aw in the shot made
inside Grand Central Station (#20),
there are times when you have to
boost the sensitivity to get more
leeway in the exposure by raising
the ISO.
Here’s why. A typical lens has a
range of full stop (1EV) openings—
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or light gathering ability—of about 6-7 stops, or EVs.
This means that you have 7 choices in changing its
light gathering ability (in fact you have fractions of a
stop between each full EV, but that doesn’t change the
outside range).
Shutter speeds in most cameras can range from
1/2000 to 30 sec in Auto Exposure mode, with some
expanding that to 1/8000 to 30 sec, which is an eternity
in photography and is rarely used, so let’s throw out
that extreme and limit the slower shutter speed range
to 2 seconds and the fastest to 1/4000 sec. That’s 14EV,
or stops (every time you halve or double shutter speed
you change the setting by 1 stop, or EV).
When you use the aperture to control the light you
are limiting yourself to within a 7EV range, on average,
while when you use shutter speed you have a 14EV
range to balance the exposure. That’s quite a difference.
Here’s a scenario that comes up often when shooting
for slow shutter speed effects (#22). You want to use
a ¼ sec shutter speed to create a flowing motion in a
stream so you set that in Shutter Priority mode. You
have ISO 400 set on the camera and, because the light
is fairly bright, at ¼ second the camera chooses the
narrowest aperture on the lens (f/22) but you still get
an overexposure warning. What’s the first thing you’d
34
do to get a proper exposure?
Right—change the ISO to 100 or to the lowest ISO
you can. Going to ISO 100 removes 2 stops, or -2EV
of exposure, so that just might bring you into a good
exposure range. What if it doesn’t? Then you have to
shoot in dimmer light (in this case find an area of the
stream shaded by trees) or use a neutral density filter
over the lens, a slow exposure aficionado’s best friend.
Available in powers like 2X, 4X, and 8X (divide the factor
by 2 to get the -EV drop of light transmission) they help
close the range gap for slow exposure work.
When working in Aperture Priority mode you have a
lot more leeway thanks to the shutter speed range—
that 14EV range we discussed. So setting any aperture
should not pose an exposure problem, although it could
pose a “steadiness” problem, so working with a tripod
or finding some way to keep the camera steady for long
exposures (like 1/15 sec and slower even with image
stabilization) is a must.
If there’s no way to use a tripod then raising the
ISO is the way out, like in this photo inside Sainte
LaChapelle in Paris (#23) where ISO 800 allowed for
an aper ture of f/5.6 to at tain sharpness from the
nearest candelabra to the vaulted ceiling ribs at a
hand-holdable shutter speed of 1/30 sec.
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25
Optional But Useful:
Manual Exposure Mode
26
36
Designated by an “M” on the mode dial—Manual
has a lot of creative effects to offer—and is the third
and last exposure mode I recommend that you get to
know. It is very useful for locking exposure on one
setting during a shooting session, for making quick
changes to exposure when working with Live View
camera models that preview the light changes in your
monitor or viewfinder, and with a special techniques
like panorama images. For many photographers these
are not everyday situations, but it is good to know
about the creative options Manual Exposure mode
can afford.
For me, the best use of Manual Exposure mode is
when I want to keep one exposure setting when working
on lighting set-ups, doing portrait sessions and when
I want to shoot quickly and spontaneously without
worrying about settings after the initial readings have
been made and “proofed” via the image review.
Let ’s f ir st look at how Manual “locks” exposure
for you. If you look at the readout of the exposure
meter when you move the camera around a scene,
even slightly, you will see them change. If you switch
to Manual the readings do not change from where
they have been set. It locks the settings at a specific
aperture and shutter speed.
How does this help you? Let’s say you are doing
a por trait session and want to be spontaneous as
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Making A Manual Reading
27
you work—fiddling around with settings will usually
make the subject uneasy or impatient as you take
readings, change them and bring the classic “take
the darn picture already” attitude and expression to
your subject’s face.
I used Manual to make a series of portraits of Brynn
(#24, #25 & #26). I set up the shots with a pleasing
backlight and her face in the shade, illuminated slightly
by a neutral reflector card held by a friend. I made
a series of exposures, reviewed them and then went
about taking a series of portraits without worrying
about the exposure settings changing. This allowed
me to be more spontaneous in my shooting and her
to be more relaxed as we worked.
So keep in mind that when working in Manual you
can take one reading and check it, as long as the light
doesn’t change you can work quickly and easily and
use your energy to engage the subject and not have
all your attention on making settings on your camera.
Note that Manual Exposure mode does not
mean you have to guess what the exposure
might be or use a light meter independent of
your camera. It certainly does not allow you
to make up any exposure you want. It actually
relies on the same metering system as the
Auto Exposure modes and then “suggests”
the proper reading, which you can follow or
ignore by manually making the aperture and
shutter speed settings yourself.
This “suggestion” the camera exposure
system makes is indicated by a hash mark
on a horizontal graph that appears in the
viewfinder or on the LCD. You then change
your settings by moving the aperture and/or
shutter speed dials so that the indicator (or
hash mark) sits in the center of that graph.
This works great for studio-lit portraits as well.
This technique can also be effective when the quality
of the light is fleeting, like morning mist or even when
photographing a rainbow that can quickly fade (#27).
So, test the first exposure in automatic and refine it,
note the settings, switch to Manual with those settings
and go for it.
Manual Exposure mode is also the best way to expose
for panorama pictures, using Sweep Panorama mode
(in some cameras) or especially if you are shooting a
set of images that you will later “stitch” together using
panorama software. It is important that you establish
one exposure (test for the one exposure that handles
the highlights and will not overexpose them) and then
place the camera on Manual mode for all of the rest of
the shots, as I did here in this photo of lake reflections
(#28) made in the Grand Tetons. Failure to do so may
result in disjointed areas of exposure and color, as
an Auto Exposure mode will adjust for each frame in
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the series. The exposure here was based on a reading
taken from the far left side of the frame.
“Tweaking” Via Manual
Cameras with Live View often give a simulation of
exposure right on the LCD. Although it is not always
100 percent accurate, the view can help you decide on
the best exposure before you expose the image. Using
the “hash mark” technique of setting the exposure
you first make aperture and shutter speed settings
by moving either/or control until the indicator rests in
the center. Set the camera to “M.” Check the LCD as
you compose. If you want it lighter move the indicator
toward the plus side and to take away exposure move
it toward the minus side. In this photo the camera
recommended exposure was fine, but I wanted a deeper,
richer contrast between the red soil and the weathered
tree remnant (#29). So after checking the preview
image I moved the shutter speed control to minus 1 to
attain the look I desired, since I wanted to maintain the
narrow aperture to get a deep depth-of-field.
“Bulb” Exposure
One subset of Manual mode is referred to as B
(or “Bulb”) exposure. In this setting you can use a
cable release—either a manual cable type release
or a remote control release—that keeps the shutter
open as long as the release is locked (which means
engaged). You can also just set “B” and hold down
the shutter release with your finger for as long as you
like, although this risks introducing a shake-producing
element into your photo. This technique can be used to
make multiple images of fireworks, thus fill the frame
38
with light, as seen in (#30).
Here’s how the shot can be done. Set the aperture at
f/8 or f/11 and the ISO at 100. In Manual mode set the
camera on “B” (for Bulb). Use your hand or an opaque
cloth to cover the lens, engage the cable release and
lock it. (If you use your finger on the shutter release
it can cause a shaky shot—which can be fun too—so
consider using a tripod.)
When a bur st goes of f uncover the lens and let
the fireworks “fall”, then cover it again. Repeat once
or twice more, depending on the pace of the show.
Check the results and adjust the aperture or the ISO
accordingly. This takes some testing and practice, but
it can be a fun technique to try. This technique is also
great for recording the streaming taillights of cars as
they rush through city streets at night or for very long
time exposures of night and day scenes that can have
a very “other worldly” effect.
S o, t hat ’s i t a s f ar a s t h e E x p o s ur e m o d e s I
recommend are concerned. There are “two to use”—
Aperture and Shutter Priority, and another to get to
know for special circumstances—Manual.
While this might seem to ignore all the other modes
your camera offers that’s the point—to get down to
the essentials of picture making without getting all
mixed up trying to figure out which of the many, many
modes in your camera to use. The truth is that digital
cameras today, to me, are over-engineered and the
modes discussed will allow you to do whatever you
want to make creative images.
In the next Chapter we’ll take the same approach
with metering pat terns and of fer you a simplified
method of making great light readings every time. Y
Metering
Patterns
Reading And Defining Light
xposure modes define how you use the
light hitting the sensor for image effects.
Metering patterns define the light that
is actually being read, how the light is
analyzed to come up with an exposure
solution and how you determine how that
analysis is made. Of course, when you put the camera
to your eye and frame a pic ture you are def ining
the area of light in the scene that will be reflected
back onto the camera’s sensor through the lens. You
“accept” certain areas and frame out other parts of
what’s before you, as in this detail from the interior
of a parking garage (#1). Here the light comes from
an open door to the right—the challenge is to expose
so that the image works not only compositionally but
how light and dark areas interact, how highlights are
handled and how you render it so that it mirrors how
you see the image. In this chapter I’ll go over some
easy ways to accomplish this by understanding how
a meter analyzes light.
I am also going to ask you to perhaps rethink the
way you may be exposing your images and particularly
which metering patterns to choose. This is not an
arbitrar y suggestion, but one that will put you in
personal control of light in your photography.
Find where the metering pattern choice controls are
located on your camera. There are usually 3 patterns
to choose fr om. Depending on the make of your
camera this includes a computer controlled exposure
system—called Matrix in Nikon cameras, Evaluative in
Canon, and “Multi-Pattern” or similar in other brands.
There’s also one called Center-Weighted (Averaging)
and one called Spot or sometimes “Partial”.
For purposes of not repeating all of the brand names
each time I’ll refer to the first pattern in the list as
simply “Multi”. On this model (#2) you choose the
pattern with a dial—the selection here is Multi, with
Center-Weighted above it and Spot below. Other
models may have you select it from the Menu or other
means and may use different symbols to indicate the
patterns—check your instruction book.
E
1
Multi-Pattern Metering
A Multi-Pat tern metering system is an amazing
feat of technology. It gathers light and often color
information from the scene you have framed, takes
the lens, the Exposure mode, the ISO you have chosen
and runs all of the information through an on-board
2
COLOR & LIGHT 39
COLOR & LIGHT
…Multi-Pattern
metering is the choice
of the large majority of
photographers and
delivers a good
exposure for almost
every lighting situation.
3
microprocessor. This computer then sor ts out the
information and comes back with a “solution” from
a data bank that matches the data supplied with a
combination of aperture and shutter speed, the light
regulators in your camera system. This happens almost
simultaneously with your pressure on the shut ter
release, and it is quite impressive.
These Multi-Patterns are becoming “smarter” with
each phase in photography’s evolution to the point
where the system can recognize a face, understand
composition and even alter color and shar pne ss
rendition when it deems it appropriate.
In fact, it’s so impressive and reliable that MultiPattern metering is the choice of the large majority
of photographers and delivers a good exposure for
almost ever y lighting situation. In this photo of a
graffiti covered wall in Berlin made under an overcast
sky (#3), Multi delivered a perfect exposure with no
effort on my part. The same goes for this seemingly
4
40
5
complex lighting situation made at the back of the
stage at a street performance (#4). It’s also usually
right on when the sun is coming over your shoulder
and lighting the scene before you, like in this western
landscape (#5).
You might wonder, why am I asking you to not use it?
The reason is that your camera has other metering
patterns that allow you to more fully engage in the
craft of photography. They put the problem of light
and its solution in your hands. They have you look at
the light and make judgments about how you want to
record it, not on how a computer thinks you should
record it. They are more demanding but will help
you to appreciate light, shadow, color and how they
interact in the world around you and create the visual
instincts that are at the hear t of the photographic
process.
Take a look at this photo of the San Francisco de Asis
Church in Ranchos de Taos, New Mexico (#6). From
where would you take the light? How deep do you want
the shadows to be? Do you want to see detail in them?
How do you control the various bright areas, like the
snow? What tonal depth do you want in the form in
the foreground? These are the kind of decisions that
6
COLOR & LIGHT 41
COLOR & LIGHT
8
7
8A
To me, photography is
more about the visual
immersion of the
photographer in
that interplay than just
grabbing images.
exposure pattern set-up, but after a few short shooting
sessions you will understand how using patterns other
than Multi make you a master of light and color and
not dependent upon a computer algorithm.
Yes, the Multi-Pattern is great for snapshots and
family occasions, or when you just want to make
simple travel photos from the window of the bus, but
these other patterns put the photographer—and all
that entails—back into photography.
Digital’s Highlight “Problem”
taking control of your exposure allows you to make.
This kind of thinking really comes to the fore when
shooting a black and white image (#7). In the days of
film, photographers worked with a system of exposure
known as the Zone System, a way of “placing” tonal
values to add fidelity to their images and to interpret
them in a very specific way. Highlights, shadows and
midtones (a range from light to dark gray) all were
considered carefully.
To me, photo gr aphy is mor e ab out the visual
immersion of the photographer in that interplay than
just grabbing images. The end result is an image, but
one that you have taken responsibility for and that is
a true representation of how you see.
This may seem like an onerous task and one that
does not take advantage of what is a rather good
42
Your camera’s sensor contains “photo sites” that
receive light energy that eventually becomes the
code that def ines the brightness, color and other
information of that site when read and translated onto
a computer monitor or LCD. But these sites have a
certain limit of the energy that they can receive, and
when too much light hits them they “dump” the excess
energy. Think of them as a bucket of a certain depth
into which water is poured; once the bucket is filled
the water spills over the edge.
That’s what happens to these sites when too much
light energy fills them—they basically dump anything
they can’t handle. If they didn’t, that light energy
would spread to other sites where they don’t belong
creating halos (or “burnt up areas” and general havoc)
within the frame.
9
9A
T h o s e w h o w o r ke d w i t h f i l m i n t h e p a s t w i l l
understand this as excessive density in negative film
and “clear”, blank areas in processed slide film. This
photo of a neighborhood in Taos, New Mexico (#8) is
harsh because the highlights are overexposed and the
shadows are “weak,” a result of poor exposure (yes,
it was done with Multi). But switching to Spot and
making some nuanced changes solved all that (#8A),
eliminated the “lost” highlight values in the scene and
recorded it as I saw it.
The way to restrain potential problems and not
have to spend time wrestling with an image file in
processing is through proper exposure—the control of
light that passes through the lens and shutter onto the
sensor. By use of the metering patterns I recommend
you can retain the rights to exposure and control it
with the knowledge of how it works.
Yes, sophisticated Multi-Pattern metering makes
brave attempts to overcome problems such as this,
but there are numerous instances when it cannot,
especially with high contrast, backlit, low light and
side-lit scenes. My stance is that you can use the two
patterns I recommend to ensure that this does not
happen and that you control the light.
Center Weighted Averaging
I’ve covered how Multi works—how does CWA read
exposures? The area in which CWA reads light is
like an oval that sits within the frame, with more
information “weighting” from the center of the oval
and less included as it moves out toward the edge of
the “egg”. It assays all the brightness values in that
area and then creates an “average” of the light energy
to create that single EV exposure we discussed.
In this photo made in a museum garden in Madrid,
Spain (#9) the statue sits in the light surrounded by
a very dark background. Switching to CWA, I moved
the framing of the image until the statue sits in the
center. I then locked the exposure on that framing
and recomposed for the composition I desired. If I had
just pressed the shutter with the original framing the
metering system would have taken much of the dark
background into consideration and yielded an exposure
similar to the overexposed photo here (#9A).
COLOR & LIGHT 43
COLOR & LIGHT
10
Check your instruction booklet
on how to engage AEL on your
camera, as it is an essential
exposure control.
Similarly, this complex photo of the Rio Grande Valley has very
high contrast between the deep shadows and the brilliant light on
the foliage (#10). I recognized the contrast and wanted to use those
deep shadows as an important part of the composition. Using CWA
I swung the camera to the upper right and took a reading, which I
then locked for this exposure.
How do you lock readings when working in CWA with Aperture or
Shutter-Priority Auto Exposure modes? There are two easy ways
to do it. One is to maintain light pressure on the shutter release
to keep the exposure set when you recompose. This takes a bit of
practice but it works fine. The other is to use a button or switch
which actives the AEL, or Auto Exposure Lock. On many Canon
cameras it is indicated by a “star” located on the upper right of
the camera’s body (#11). Here is the Nikon AEL button in a similar
position (#12). Check your instruction booklet on how to engage
AEL on your camera, as it is an essential exposure control.
Keep in mind that this method is designed to capture images
44
11
12
13
where the lighting is complex and be aware of the highlight
areas. All you need do is point the camera at the highlight
area (see “Spot metering” below for when the scene is
dominated for bright areas, keeping in mind that CWA reads
a larger area and should include some other tonal values)
engage Exposure Lock and reframe if needed.
In this way of working the lock function is key—so learn
how to use it and practice until you get it right. You can
see if you are doing it correctly by engaging Exposure Lock
and then making sure the shutter and aperture values do
not change when you move the camera to another part of
the scene. Do note that this lock becomes “unlocked” after
you make the shot.
All of this is quite easy. Consider the light in the scene.
L ook for the highlight value s. Fr ame in their gener al
direction. Lock the exposure. Recompose and shoot. In
this photo made outside Cocoa Beach, Florida’s famous Ron
Jon’s surf shop (#13), there’s a large area of deep, dark
sky that could throw off the exposure. I pointed the finder
toward the lower portion of the frame, locked the exposure
and then recomposed to get around the potential lighting
problem. And if you ever wondered how to get great shots
of a dazzling sunrise or sunset sky (#14, photo by Grace
Schaub), CWA is the key. Just point the camera at the sky
(not the sun!) lock the exposure, recompose if needed and
shoot. The ground will become a silhouette, but generally
it’s there to play a supporting role and getting detail in it
is not the point of the shot.
The light was highly directional in the morning at this
14
© Grace Schaub
COLOR & LIGHT 45
COLOR & LIGHT
15
flea market in Berlin, Germany (#15) and to make sure the
bright area on the left side was recorded properly I swung
the camera to the left, locked the CWA exposure and then
recomposed to include the other areas in the scene.
Sometimes you might have to walk or zoom in to accomplish
this, then lock the exposure and either walk back to your
original framing or zoom back to the initial focal length. In this
photo made inside a slot canyon in Tent Rocks, New Mexico
(#15A) I walked over to take a reading of the light reflecting
off the sandstone wall using CWA, locked it, resumed my
original point of view and made the shot. This could also
have been accomplished using a Spot metering pattern but I
just wanted to illustrate that CWA can be useful in numerous
shooting situations if you adapt to the scene.
By now I trust you are getting the gist of how to use this
light control. Look at this flea market scene in Madrid, Spain
(#16). How would you read it? All you need to do is swing
the camera to the left side, lock the reading and recompose.
There are some caveats when using CWA. The first is that if
the scene is composed chiefly of highlights—such as brightly
lit sun or a white church front in full light under a blue sky—
use of this pattern will in fact turn that bright white quite
gray, although there are ways around that. But these types
of scenes are more suited to and more easily done using a
Spot metering pattern.
Second, do not include very bright light sources in your
framing (such as the sun or a direct spotlight) as this will cause
severe underexposure of the rest of the scene. Remember,
46
15A
16
this pattern averages light readings, so if the sun is
EV 22 (or higher) the average will be skewed so high
that darker areas will become silhouettes or lost in
the darkness and all you’ll record is the light source.
Spot Pattern
Spot—sometime called “partial” metering—allows
you to make very specific light readings within the
frame. The spot is a very small area within the finder,
usually dead center, that really only includes anywhere
from 2-5 percent of the entire field of view. In some
cameras you can broaden the area the spot covers.
Spot in digital is mainly for highlight control. It is
normally used in conjunction with a function known
as exposure compensation, activated by a +/- marked
button on your camera or from within the camera’s
menu or (if shooting in Manual mode) by moving the
hash mark toward the plus side of the graph. In fact,
Spot pattern is an excellent companion to Manual
exposure mode. Even fairly basic cameras have this
control (#17), usually indicated by a +/- button on the
camera’s body. You engage it and then move a command
dial as you follow an LCD or viewfinder +/- guide that
17
COLOR & LIGHT 47
COLOR & LIGHT
18
19
18A
19A
48
21
20
indicates plus or minus exposure from the reading.
You can (with some cameras) “move” the spot area to
various points within the frame, but I find that keeping
it dead center, it’s usual “default” position, is best.
When a Spot reading is made it “moves” the brightness
it reads to what is called a middle gray value, so a bright
white is then exposed as a darker value, or made grayer.
To counter this you apply exposure compensation by
adding exposure. (In the same way, “placing” the Spot
area over a dark area will add exposure to it, making it
lighter than it appears to your eye.)
A few years back I went on a flower and herb guided
walk and photographed the specimens as the leader
cut and explained them. I took along a white board
and laid the items on them, took a Spot reading over
the white board and added +1.5 EV (#18) and got the
exposure correct every time (and didn’t have to fuss
with exposure after the initial reading). Without adding
exposure after the reading the backgrounds would
have been quite gray (#18A).
Here’s a classic Spot metering scenario, a white
clapboard church in New England. Proper exposure is
easily done. Here’s the exposure with spot of the wall
and no exposure compensation (#19) and here’s one
with +1EV exposure compensation (#19A).
But Spot doesn’t always need exposure
c o mp e n s a t i o n. Sp o t p a t t e r n i s gr e a t f o r s t a g e
performances where spotlights are the rule. In this
photo of a per formance by Countr y Joe McDonald
I “placed” the spot over him seated on the distant
22
22A
stage and got a “right on” exposure (#20). Any other
pattern would have resulted in a completely overexposed image.
For this photo of a palm frond—which I converted to
black and white—I wanted the bright frond to contrast
strongly with a darker (than I saw) background, so I
just placed the spot on the bright area of the frond
and made the exposure (#21). Neither this shot nor the
performance shot required any exposure compensation.
And just to convince you about choosing Spot, here’s
a photo made with Multi (#22) and one with spot placed
right on the bright yellow area of this blossom (#22A)
with no compensation. Note how Spot not only handles
the light but also enriches the color experience.
COLOR & LIGHT 49
COLOR & LIGHT
23
23A
24
A (Final) Word: Shadow Detail
I have stressed throughout this issue the need to
control highlights in digital imaging. But what about
the shadows? Are we condemned to always have them
come out dark and detail-less? First, not every scene
is of such high contrast that shadows will always be
very dark. As you work with CWA you will see how this
works and how paying attention to the highlight area
(but also including some shadow area) will result in
“open” light values.
Second, there is a lot of detail in the shadows that
you might not see right af ter you make the shot
(especially on a small LCD). Those details can be
brought out with fairly simple processing tools. In
fact, it can be rather amazing what lies hidden within
them. In this photo I could barely see the bicycle rider
coming out of this construction tunnel but with some
easy post processing, she appeared! (#23 & #23A).
50
And finally, knowing that shadows might go dark
can guide you in compositional decisions and you will
begin to see not only the bright light but also how the
shadows can add depth, drama and dimensionality to
your images (#24).
Practice Makes Perfect
As you work with the metering techniques covered in
this issue test them under different lighting situations
until you get a feel for them. I guarantee you will be
amazed at what results. Using these three patterns
and two exposure modes might seem difficult at first,
but once you practice with framing for the highlight,
locking the exposure, exposure compensation and
recomposing if needed, and choosing aperture and
shutter speed combinations for specific effects, you
will begin to understand how they give you complete
control over exposure and light in your images. Y

Petersens PHOTOgraphic

Transcription

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