EXPOSURE For Outdoor Photography MICHAEL FRYE
In photography, creativity and technical
skill are both essential. A wonderful eye and
imagination might help you find fantastic
compositions that nobody else would see,
but if the images are three stops overexposed,
and unintentionally blurred, no one will be
able to appreciate your geniustheyll just
see washed-out, fuzzy photographs. Good
technique can amplify a photographs mes-
sage, and bad technique can detract from it.
The most essential technical skill a photogra-
pher must master is exposure. On the surface,
exposure seems easy. Its simply a matter of
making the image bright enoughnot too
dark, and not too light. But the endless variety
of light makes exposure challenging. No two
situations are the same, so there can be no
exact formula for getting the right exposure.
On the other hand, exposure doesnt need
to be overly complicated. The fundamental
controlsshutter speed, aperture, ISO, light
metersare easy to understand. And digital
cameras have eliminated a lot of the guesswork.
We can use the cameras LCD screen, andeven
betterthe histogram to evaluate the exposure.
Well start with these fundamentals, and then Ill
show you ten practical, real-life examples where
Ive used these principles to control the exposure,
the sharpness, and the photographs message.
Introduction
WHY DOES EXPOSURE MATTER?
Understanding the fundamentals can help you quickly find the
right exposure to capture a fleeting moment like this.
2
The exposure for any given image is determined by four things: the light, shutter speed, aperture, and ISO. You cant control the light unless youre in a studio. The other threeshutter speed,
aperture, and ISOyou can control, and these are known as the Exposure Triangle.
The Exposure Triangle
A relatively fast shutter speed of 1/250 of a second froze the motion of
Nevada Falls in Yosemite, capturing the texture of the spray.
A typical viewfinder exposure scale in manual
mode, showing the shutter speed (250, or 1/250
of a second) and aperture (5.6, or f/5.6).
Shutter speed is the length of time the cameras shutter is open. The shorter the du-
ration, the less light reaches the sensor, and the darker the photograph. The longer
the time, the more light reaches the sensor, and the brighter the photograph.
Shutter speeds are usually brief, mere fractions of
a second: 1/60 of a second, 1/125 of a second, etc.
But on most cameras all you see is that second
number: 60, 125, 250, and so on. The first part of
the fraction, the numerator (1/), is omittedyou
just have to assume its there. So if you see the
number 30, that means 1/30 of a second. If you
see the number 60, that means 1/60 of a second.
Theres an exception, of course, just to make
things more complicated. When shutter speeds
get really slowone second or longerwere
not talking about fractions any more. When
this happens, most cameras indicate this by put-
ting the second symbol (") after the number.
So 1" is one second; 2" is two seconds, etc.
But unless you see that second (") symbol,
youre looking at a fraction, and the higher
the number, the shorter the shutter speed. The
shorter the shutter speed, the less light reaches
the sensor, and the darker the photograph.
Shutter speed also affects movement, both of
the camera and subject. A faster shutter speed
(higher number) will freeze motion, allow-
ing you to handhold the camera without blur,
and get sharp images of moving subjects. A slow
shutter speed, on the other hand, may require
using a tripod to avoid camera shake, and will
blur moving subjects. For more about shutter
speeds and movement, see case studies 4 and 5.
SHUTTER SPEED
3
APERTURE
The Exposure Triangle
Every lens has a diaphragm that expands and
contractslike the pupil in your eye. The
size of this opening is the aperture. The big-
ger the aperture, the more light reaches the
sensor, and the brighter the photograph. The
smaller the aperture, the less light reaches the
sensor, and the darker the photograph.
The numbers describing the size of this open-
ing are called f-stops, and, unfortunately, they
can be a bit confusing. With aperture, the bigger
the number, the smaller the size of the open-
ing. So f/2.8 is a large aperture (a large open-
ing, letting in more light), while f/22 is a small
aperture (a small opening, letting in less light).
If you must know, f-stop numbers are actually
ratios, or fractions. f/4 is 1:4, or 1/4. f/16 is 1:16,
or 1/16. So the bigger the f-stop numbers, the
smaller the fraction. (And if you really must
know, the ratio is aperture to focal length.)
But these details arent important. Just remember
that with apertures and f-stops the numbers
are inverted: a bigger number means a smaller
opening, and less light, while a smaller number
means a bigger opening, and more light.
Aperture also affects more than just exposure.
The larger the aperture (lower number), the less
depth of field, while the smaller the aperture
(higher number), the more depth of field. Or
to look at it another way: bigger number, big-
ger depth of field, smaller number, smaller
depth of field. For more about aperture and
depth of field, see case studies 2 and 3.
A small aperture (f/22) kept both foreground and background
in focus in this photograph from Death Valley.
4
ISO
The Exposure Triangle
While shutter speed and aperture determine how
much light reaches the sensor, ISO describes
how the sensor reacts to that light. The higher
the ISO number, the more sensitivity, and the
greater the sensors light-gathering capacity.
That extra sensitivity means that less light has to
reach the sensor to create the desired exposure.
This extra sensitivity has some big advantages.
For example, by using a higher ISO, and gain-
ing a faster shutter speed, you might be able
to hand-hold the camera in dim light where
you might otherwise need a tripod. Or, you
could also freeze a subjects motion indoors,
at dusk, or in other low-light situations.
But this greater sensitivity comes at a price.
The higher the ISO, the more noise youll get.
Noise is like film graina distracting dot pat-
tern across the photograph. High ISOs can also
create other artifacts, like posterization, where
smooth areas like sky or water become blotchy.
So like many things in photographyand in life
raising the ISO is a trade-off. A high ISO setting
can give you the convenience of hand-holding, or
allow you to freeze subject motion in dim light,
but the image quality will suffer. In most situations
you should use the cameras native ISO (usually
100, but with most Nikon DSLRs the native ISO is
200) to get the best image quality. But if you need
that extra sensitivity, use itits better to have
a grainy but sharp image than a blurred one.
One more thing: avoid using the automatic ISO
setting, as this can override your choices. If you set
a faster shutter speed to darken the exposure, for
example, the camera may boost the ISO to try and
lighten the photograph back up! So you must turn
off automatic ISO to have any control over exposure.
STOPS
Understanding this basic photographic terma stop (or f/stop)is essential
to understanding exposure. Any time you double or halve the amount of light
reaching the sensor, youve altered the exposure by one stop, or a full stop.
Any time you double or halve the length of time the shutter is open, you
double or halve the amount of light reaching the sensor, and therefore change
the exposure by one full stop. A shutter speed of 1/125 of a second is twice as
long as 1/250 of a second, and will allow twice the amount of light to reach
the sensoror, in other words, it will increase the exposure by one stop. A
shutter speed of 1/500 of a second is half the duration of 1/250 of a second,
and will allow half the amount of light to reach the sensordecreasing the
exposure by one stop.
With the aperture the numbers get a little more complicated. A full-stop
sequence goes like this: f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32. So
doubling or halving the number is actually a two-stop change.
Most cameras today have the shutter speed and aperture dials set to one-third
stop increments. So rather than seeing the shutter speed jump from 30 to
60 to 125 (1/30 to 1/60 to 1/125 of a second)full stopswhen you turn the
shutter speed dial the numbers go from 30 to 40 to 50 to 60 to 80 to 100 to
125a third of a stop for each click. With the aperture, you might go from 4 to
4.5 to 5 to 5.6 to 6.3 to 7.1 to 8again, a third of a stop with each click.
Now I dont know about you, but all these numbers are starting to make my
head hurtand I do this stuff for a living. But all you have to remember is that
each click of the dial changes the shutter speed or aperture by one-third of a
stop, and you need to move the dial three clicks to make a full stop changeto
double or halve the amount of light reaching the sensor.
ISO also usually changes in one-third stop increments: 100, 125, 160, 200, 250,
320, 400, etc. With ISO, doubling or halving the number doubles or halves the
sensitivity of the sensora one stop change.
5
Increasing the ISO to 1600 allowed me to use a fast shutter speed (1/250 of a second) to freeze the motion of these Ross geese in dim, pre-dawn light.6
Metering Modes
Every modern camera comes with a built-in
light meter to measure the light reaching the
sensor. Most DSLRs have three or four metering
modes. The default is usually a smart mode,
which uses software algorithms to evaluate
the light and dark areas within the viewfinder
and guess the right exposure. Nikon calls this
Matrix metering; Canon calls it Evaluative.
Most DSLRs also have centre-weighted meter-
ing, which measures the entire scene within the
viewfinder, but with more emphasis on the centre.
Many higher-end cameras also have a spot meter
mode, which measures only the light from a small
circle in the centre of the frame, or in an area
that corresponds with your chosen focus point.
Which mode should you use? Spot meters are
tricky, and can throw your exposures way off if
you dont know what youre doingwhich means
understanding the Zone System. I talk about the
Zone System in case study number 9, but in the
mean time, choose either centre-weighted or one
of the smart modes. The choice doesnt really
matter, since, despite the manufacturers claims,
the readings from centre-weighted metering are
usually within a third of a stop of the smart modes.
Any light meter will struggle with high-contrast scenes like this one of Yosemites Horsetail Fall.
While meters are good starting points, histograms provide a more precise way of judging exposure.
7
Exposure Modes
Most DSLRs these days come with at least four
exposure modes: program, aperture-priority, shutter-
priority, and manual. Some also have modes for
specific situationslandscapes, portraits, action, etc.
What do these terms mean? Its actually pretty simple.
In program mode, the camera takes the light meter
reading and automatically chooses both the aperture
and shutter speed. In landscape, portrait, or ac-
tion modes the camera also chooses both shutter
speed and aperture, but in an action mode it will fa-
vour a faster shutter speed, while in landscape mode it
will choose smaller apertures for greater depth of field.
In shutter-priority mode, you pick the shutter speed,
and the camera automatically selects the aperture
based on the light-meter reading. In aperture-priority
mode, you pick the aperture, and the camera au-
tomatically selects the shutter speed, again based
on the light-meter reading. In manual mode,
you choose both the aperture and shutter speed,
while the cameras light meter serves as a guide.
Which mode should you use? All have their advan-
tages and disadvantages, but if you really want to
understand exposure you should learn to use manual
mode. When you set both the shutter speed and
aperture yourself youll gain a better understanding
of how these fundamental photographic tools work.
Youll begin to take control of your photographs rather
than letting the camera make decisions for you.
Once you have a solid understanding of manual
exposure you can use shutter-priority or aperture-
priority modes more effectively, because youll
know whats happening under the hood.
Because I think this is the best way to understand
exposure, all the examples and exercises in this
book will be geared to using manual mode. If
youve never used manual exposure before, this
might seem daunting, but trust me, its not that
difficult, and youll thank me for it later.
Learning to use manual mode will deepen your understanding of
exposure and its fundamental components, allowing you to make good,
quick decisions when trying to capture photographs like this.
8
Reading Histograms
With film, exposure always involves some guesswork. But with
digital cameras you can tell immediately whether the right
amount of light reached the sensor by looking at a histogram.
This ability to instantly evaluate exposure is a game changer
the single biggest advantage of digital photography over film.
But many photographers are still guessing about exposure
because theyre unable to decipher the histograms cryp-
tic messages. Instead, they judge exposure by how bright
the image looks on their cameras LCD screen. But while
those little screens are extremely useful for many things,
evaluating exposure isnt one of them. There are too many
variables: screen quality (usually bad), the LCD brightness
setting in the camera, and the amount of ambient light.
A histogram is a much better way to judge exposureif
you know how to read it. If you havent figured out
how to display a histogram on the back of your cam-
era, youll have to spend some quality time with that
fascinating book, your cameras manual. Once you
know how to view a histogram, what does it mean?
A histogram is a pixel map. It shows how dark and light
pixels are distributed within your photographlight
pixels are on the right, dark pixels on the left. The shape
of the histogram doesnt matter. In other words, dont
worry if parts of the histogram shoot off the top, or
whether theres a spike somewhere in the middle. The
only sections that matter are the right and left edges.
If any pixels are pushed up against the right edge, that
means parts of the image are overexposedwashed out. If
any pixels are pushed up against the left edge, that means
parts of the image are underexposedblack. Most cameras
also have an overexposure warningcommonly called the
blinkieswhere overexposed parts of the photograph
flash or blink. Some cameras also have an underexposure
warning, which shows underexposed, black shadows.
The most important parts of a histogram are
the right and left edges. This histogram shows
pixels pushed up against both edges, indicating
overexposed highlights and underexposed shadows.
A properly-exposed medium-contrast scene,
with nothing pushed up against either end of
the histogram.
9
Handling High-Contrast Scenes
In most scenes, you should be able to get detail in both
highlights and shadows. That is, the histogram shouldnt
touch either the right or left edge if you make the right
exposure. But in some situations the contrast is too great
for the cameras sensor to handle, so its impossible to avoid
either washed-out highlights (a spike at the right edge of
the histogram), black shadows (a spike at the left edge of
the histogram), or both. In these cases, its usually better to
retain detail in the highlights and sacrifice shadow detail.
When looking at the histogram, its better to have pixels
pushed up against the left edge than the right edge.
Why are highlights usually more important than shad-
ows? First, our eyes are drawn to bright areas, so view-
ers immediately notice if theyre overexposed. Second,
in real life we can always see detail in bright spots, but
we cant always see detail in shadows. It seems un-
natural to find washed-out highlights in a photograph,
yet it feels perfectly normal to see regions of pure black.
So if you cant have both, 90 percent of the time you
should sacrifice the shadows and keep the highlights. In
most photographs, the lightest pixels should be close to
the right edge of the histogram, but not touching it.
Histogram for a high-contrast scene with a spike at
the right edge, indicating overexposed highlights.
Histogram for a high-contrast scene with pixels pushed up
against the left edge, indicating underexposed shadows, but
properly exposed highlights. In most cases this is preferableif
you cant get both, its better retain detail in the highlights and
let the shadows go black.
10
The Short Answer
This bears repeating: most of the time, the lightest pixels should be close to the right edge of the histogram,
but not touching it. If theres a large gap between the lightest pixels and the right edge of the histogram,
the photograph is underexposed. If any pixels touch that right edge, the photograph is probably over-
exposed. For most images, just make sure the lightest pixels dont touch the right edge, but are near it.
There are two main exceptions to this. First,
when the photograph includes the sun itself, or
the sky next to the sun, its okay for these areas
to be overexposed. Theyre too bright to see
in real life, so its okay if such areas lack detail
in photographsit looks natural. The blink-
ies come in handy here: while the histogram
tells you that something is overexposed, the
blinkies show which parts of the image are
washed out, and how large those areas are.
Second, with digital photography its possible to
blend two or more exposures together with Pho-
toshop or HDR software to capture both highlight
and shadow detail, even in high-contrast scenes.
In these cases you still want to capture one image
with the lightest pixels near, but not touching,
the right edge of the histogrambut then also
make one or more lighter exposures, including
one with nothing pushed up against the left edge
of the histogram. This ensures that you have
shadow detail as well, and all the image informa-
tion you need to blend these exposures together in
software. For more about this, see case study 10.
So now that you understand the basicsshut-
ter speed, aperture, ISO, histogramsits
time to look at some examples and apply
this knowledge to real-life situations.
Underexposed
the brightest pixels
arent close to
the right edge of
the histogram.
Overexposed
a spike at the
right edge of
the histogram.
Proper exposure
the brightest
pixels near, but
not touching, the
right edge of
the histogram.
11
Case Study 1: Sierra AspensUSING THE HISTOGRAM TO FIND THE RIGHT EXPOSURE
Backlight made these aspen leaves glow, but
the sun was sinking behind a ridge, and I knew
I had just minutes to capture this scene. With
a still subject, and the camera on a tripod, the
shutter speed didnt matter. The scene had
moderate depth, so I started by setting a mid-
dle aperture of f/11. With that f-stop, centre-
weighted metering, in manual exposure mode
at 100 ISO, the meter indicated a shutter speed
of 1/60 of a second. But when I took the photo
the aspens looked washed out on the cameras
LCD screen, the histogram showed a spike
at the right edge, and there were small areas
of blinkies in the brightest leaves, indicating
that parts of the image were overexposed (A).
I quickly turned the shutter speed dial three
clicks to the right to 1/125 of a second, one
stop faster (and darker) than 1/60and pressed
the shutter button again. Much better! The
histogram showed pixels near, but not touch-
ing, the right edge, while the aspens had
better colour, and stood out dramatically from
the darker background (BFollowing page).
Now I suppose some people might prefer the
lighter version. Exposure, like everything in
photography, is subjective. Theres really no
such thing as the correct exposuretheres
only the exposure that works best for you, and
captures the scene the way you visualize it.
What caught my eye here was the contrast
between the sunlit aspens and the shaded
background. I wanted that background to be
dark so the yellow leaves would stand out
clearly. And I certainly didnt want those
leaves to look faded and washed out, since
theyre the focal point of the image. So an
exposure one stop darker than the meter
reading gave me what I was looking for.
Now why did the meter get this one wrong
(for me at least) in the first place? Because
light meters are dumb, of course! With centre-
weighted or smart modes, the meter is
simply measuring the amount of light reflect-
ing back at the camera, and averaging the
light and dark tones together. It doesnt know
what parts of the scene are important to you.
Also, meters dont know whether theyre
pointed at something white, or black, or in-
betweenthey just measure the amount of
light reflected back at them. Naturally, white
objects reflect more light than black objects.
Since meters are calibrated to middle grey
theyre easily fooled by anything that isnt a
medium tone or colour. The tendency is for the
meter to try to lighten dark objects and darken
light objectsto make them middle grey.
A
USING THE HISTOGRAM TO FIND THE RIGHT EXPOSURECase Study 1: Sierra Aspens
13
In this scene, when averaging everything
together, the meter gave more weight to the
shaded areas and tried to lighten them to
a middle tone. Unfortunately that pushed
the most important part of the scenethe
treestoo high, and they became washed
out. So I had to deviate from the meter read-
ing and set an exposure one stop darker. The
meter got me closejust not close enough.
In this case I used a faster shutter speed
to darken the exposure. I could have used
a smaller aperture (bigger f-stop number)
instead, and here either would have worked.
But when using a tripod with a stationary
subject I usually set the aperture first to get
the desired depth of field, and then adjust
the shutter speed to get the right exposure.
I could also have done the exact same thing
in aperture-priority automatic mode. At f/11,
100 ISO, in aperture-priority mode, the camera,
guided by the same light meter (and with no
exposure compensation), would have chosen
the same shutter speed: 1/60 of a second. After
looking at the histogram I could have used
the exposure-compensation dial to darken the
image by one stop. In aperture-priority mode
the f-stop would have stayed the samef/11
but the camera would have chosen a faster
shutter speed: 1/125 of a second. Which is
exactly what I ended up with in manual mode.
See how understanding manual exposure
will allow you to use automatic modes more
intelligently? When you adjust the exposure-
compensation dial in aperture-priority mode,
what youre really doing is changing the
shutter speed. When you turn the dial to -1.0,
youre telling the camera to use a faster shutter
speed to darken the exposure. When you set
the compensation to +1.0, youre telling the
camera to use a slower shutter speed to let in
more light and increase the exposure. If youre
hand-holding, a faster shutter speed would
be fine, but a slower shutter speed might lead
to camera shake. So if you use any automatic
exposure mode, you need to pay attention
to what its doing. Better yet, use manual
mode so youre conscious of all the settings.
By the way, live view can be a great as-
set for finding the right exposureif you
can see a histogram. Using a histogram
in live view, I could have ignored the
cameras meter and dialed in the right
shutter speed before taking the picture.
USING THE HISTOGRAM TO FIND THE RIGHT EXPOSURECase Study 1: Sierra Aspens
B
14
PHOTOGRAPH BOTH LOW AND HIGH-CONTRAST SCENES
Case Study 1: Sierra Aspens
1) First, use a tripod so you dont have to worry about
camera shake. Then set the aperture. Pick a middle f-stop
like f/8 or f/11 if depth of field is not an issue. Pick a small
aperture like f/16 or f/22 if you have both near and distant
objects in the frame (more about depth of field in the
next example).
2) Use centre-weighted or smart metering to set the
shutter speed. Most cameras show an exposure scale in
manual mode. Simply turn the shutter speed dial until the
exposure indicator lines up with zero.
3) Then take a photo and check the histogram. If it looks
okayif the brightest pixels are near, but not touching, the
right edge, and you dont see any blinkiesthen youre
done. If not, adjust the shutter speed. If you see a spike
at the right edge of the histogram, or you see blinkies,
that means the image is too light, so use a faster shutter
speed to darken the exposure. If the histogram is pushed
to the left, and theres a large gap between the brightest
pixels and that right edge, then use a slower shutter
speed to lighten the exposure. Then take another photo,
and if necessary, keep adjusting until the image and the
histogram look right.
Remember that on most cameras, each click of the
shutter speed dial changes the exposure by only a third
of a stop, which is hardly noticeable. To see a significant
difference, click the dial three times to change the
exposure by one full stop. And once youve made the first
exposure, ignore the meter and use the histogram to guide
your adjustments.
If you dont have a tripod, start by setting a reasonably
fast shutter speed, like 1/125 of a second, then adjust the
aperture until the exposure indicator lines up with zero. If
the initial histogram is off, keep adjusting the aperture to
change the exposure until you get it right.
With the high-contrast scene, when you get the histogram
into the right spotnear, but not touching, the right
edgethe photo might look too dark on your cameras
LCD screen. Thats okay; exposure for high-contrast
scenes is often a compromise, and youll probably like the
seemingly too-dark exposure better when you see it on
your computer screen. But just in case, it wouldnt hurt to
take a lighter one!
PHOTOGRAPH TWO DIFFERENT SUBJECTS: ONE HIGH-CONTRAST SCENE WITH A MIXTURE OF SUN AND SHADE, AND ONE LOW-CONTRAST SCENE WHERE EVERYTHING IS IN THE SAME LIGHT. USE MANUAL MODE, AND FOLLOW THESE STEPS:
EXERCISE
15
Case Study 2: Three BrothersGETTING EVERYTHING IN FOCUS
Now that you have a better understanding of how to
read a histogram and adjust the exposure manually, its
time to take a closer look at one of the fundamental
exposure controls: the aperture. In addition to altering
exposure by controlling how much light passes through
the lens, the aperture also affects depth of field.
What is depth of field? Its how much of the im-
age is in focus from front to back. You can have
one thing in focus, while everything in front of or
behind that object is out of focus. Or you can try
to make every part of the photograph sharp.
With most landscape images, I want everything to be in
focus. But in this scene of Three Brothers in Yosemite the
depth of field was extremethe snow mounds at the bot-
tom of the frame were only two or three feet from the cam-
era, while the background peaks were at least a mile away.
I knew this photograph would require a small aperture
the smaller the aperture, the more depth of field. Is f/22
a small aperture or a large one? What about f/4? Heres
an easy way to remember: the greater the f-stop number,
the greater the depth of field; the smaller the f-stop
number, the smaller the depth of field. So a large num-
ber, like f/16 or f/22, means great depth of field; a small
number, like f/4 or f/5.6, means shallow depth of field.
Wide-angle lenses have inherently greater depth of field,
and I wanted the near-far perspective they create, so I
chose a 24mm focal length. With the camera on a tripod,
and the subject sitting still, I didnt need to worry about
using a slow shutter speed, so I started by setting my lens
to its smallest aperture: f/22 (big number, big depth of
field). Then I focused manually using the procedure in
the sidebar Focusing for Maximum Depth of Field.
Next, as in the last example, I set the shutter speed to
the light meters recommendation: 1/30 of a second (at
100 ISO). This turned out to be just rightthe histogram
looked perfect. Although this scene had a lot of contrast,
apparently the light and dark areas balanced out.
To get great depth of field, use a wide-angle lens,
focus carefully, and set a small aperture like
f/16 or f/22. A tripod helps, as the small aper-
ture usually requires a slow shutter speed.
GETTING EVERYTHING IN FOCUSCase Study 2: Three Brothers
17
FOCUSING FOR MAXIMUM DEPTH OF FIELDCase Study 2: Three Brothers
FOCUSING IS CRITICAL WHEN TRYING TO GET MAXIMUM DEPTH OF FIELD. FOCUS ON THE FOREGROUND AND THE BACKGROUND WILL LOOK SOFT. FOCUS ON THE BACKGROUND AND THE FOREGROUND WILL BE BLURRED. THE OPTIMUM FOCUSING POINT (HYPERFOCAL DISTANCE) IS SOMEWHERE IN BETWEEN. TO FIND IT, FOLLOW THESE STEPS:
a) Use manual focus, then first focus on the object closest to
the camera, and note the distance on your focusing ring. In this
illustration, its three feet away.
b) Next, focus on the farthest thing from the camera, and
once again check that distance on your focusing ring.
Here its at infinity.
c) Set your focus halfway between these two spots on your
focusing ring.
18
Case Study 3: ConeflowersUSING SHALLOW DEPTH OF FIELD
Standing among these tall coneflower stalks, I looked for a way to simplify
the scene. The obvious solution was to make a portrait of one flower,
while using a wide aperture to throw the background out of focus.
I knew that the more distant the background, the more out of focus
it would be, so I looked for an angle where the background flow-
ers were several feet away from my main subject. I also knew that
the inherently shallow depth of field of a telephoto lens would help
throw the background out of focus, so I used a 200mm lens.
With this lens set to its widest aperture, f/4 (small number, small
depth of field), the background looked nice and soft, but some
of the petals on the main flower were out of focus. I tried stop-
ping down the aperture to f/8, but when I pressed my depth-of-field
preview button the background flowers started to come into fo-
cus, and became too distracting. So I kept the aperture at f/4.
With images like this at least one important visual focal point needs
to be sharp, so I focused manually on the green button at the top
of the flower. The contrast was low, making this an easy exposure. I
manually set the shutter speed to the meters recommendation, 1/15
of a second (at 100 ISO), and this turned out to be just right.
USING SHALLOW DEPTH OF FIELDCase Study 3: Coneflowers
20
DEPTH-OF-FIELD PREVIEW
Case Study 1: Sierra Aspens
When you look through the viewfinder of an SLR camera,
youre not always getting an accurate view of whats in
focus. Even though you may have the aperture set to f/16,
the diaphragm in the lens stays wide open at f/2.8 or f/4 (or
whatever the lowest f-stop number is on your lens) until you
press the shutter. Then the mirror flips up, the diaphragm
closes down to f/16 (or whatever aperture youve set), and
the shutter opens.
This design allows plenty of light to come through the lens,
and makes the viewfinder nice and bright when youre trying
to compose and focus. But you dont see an accurate view of
the depth of field unless youre using the widest apertureor
you use the depth-of-field preview.
The depth-of-field preview is a button somewhere on the
camera (usually near the lens mount) that doesnt seem
to do anything except make the viewfinder go dark. But it
does have a function: pressing the button closes down the
aperture to f/11, or f/16, or whatever its set to, so that you
can actually see whats in focus through the viewfinder at
that f-stop.
Of course because youve closed down the aperture, less
light is coming through the lens, so the viewfinder gets
really dark! Nevertheless, it can still help you determine
whether youve really got everything in focus in landscape
photographs, or whether background elements have become
too distracting with close-ups or portraits.
In this first shooting-star photograph (A), I kept the aperture
nearly wide-open at f/5.6. The background was nice and soft,
but some of the flowers were out of focus. In the second
example I stopped the aperture down to f/16 (B). With the
depth-of-field preview I could see that most of the flowers
were in focus, but some background leaves had become
visible. Which is better? Thats always subjective, of course.
In this case it bothers me that some flowers are out of focus
at f/5.6, so I probably prefer the greater depth of field at
f/16, even though the background is more distracting.
Make two different photographs, one with shallow depth of field to isolate the subject, and one with
great depth of field where everything is in focus from near to far.
For the shallow depth-of-field image, use a telephoto lens (the longer the better), make sure at least
one thing is sharp, and use a wide aperture like f/2.8 or f/4 to throw the background out of focus.
For the photograph with great depth of field, use a wide-angle lens and make sure everything is
sharp. You should have an object very close to the camerano more than 5 feet awayplus something
distantat infinityand use a small aperture like f/16 or f/22 to get everything in focus. Use the
focusing technique I describe in Focusing for Maximum Depth of Field, page 18.
EXERCISE CONTROLLING DEPTH OF FIELD
A B
Case Study 4: Upper Yosemite FallFREEZING MOTION
Both shutter speed and aperture control the
exposurehow bright the image is. Aperture,
as weve seen, also affects depth of field. Shut-
ter speed, on the other hand, affects move-
mentboth camera movement and subject
movement. Faster shutter speeds freeze motion,
while slower shutter speeds blur motion.
For getting sharp hand-held photos, the shut-
ter speed should be equal to or greater than the
length of the lens. So if youre using a 20mm lens,
the shutter speed should be 1/20 of a second or
faster. If youre using a 100mm lens, the shutter
speed should be at least 1/100 of a second. With
image stabilization, you may be able to get away
with slower shutter speeds than this, but you
can get sharp photos at any shutter speed with
a sturdy tripodunless the subject is moving.
Photographing Upper Yosemite Fall one spring
afternoon, I was struck by the patterns and
textures of the water. Gusts of wind would
blow the fall almost sideways, causing ar-
rows of spray to shoot out underneath.
The camera was on a tripod, but I needed a fast
shutter speed to freeze the waters motion and
show its texture. How fast? The answer depends
on how quickly the subject is moving across
the picture. A relatively slow shutter speed
can freeze something moving toward you or
away from you, but the same object moving
across the frame may need a much faster shut-
ter speed. Experience is the best teacher, but a
zoomed-in look at your LCD screen can help.
This scene had little depth, but shutter speed
was obviously important, so I set that first. Previ-
ous experience told me that 1/125 of a second
would be fast enough to freeze the waters mo-
tion. Then, with the ISO at 100, I adjusted the
f-stop until the meter indicated I had the correct
exposure (which happened to be at f/8). But
the meter was apparently fooled by all the dark
shadows, and the resulting histogram had a spike
on the right edge, while the waterfall looked
washed out and showed lots of blinkies (A).
FREEZING MOTIONCase Study 4: Upper Yosemite Fall
A
23
Since shutter speed was the primary consideration I left that alone, and turned the aperture
dial three clicks to the right (one full stop) to f/11. (On most cameras, turning either the
shutter speed or aperture dial to the right darkens the photo, while turning them to the
left lightens it.) I made another test shot, and this time the histogram looked perfect.
Then I just had to wait for the right moment (B).
Of course, fast shutter speeds can freeze the motion of many subjects: flying birds, people
in action, cars, planes, etc. To freeze movement, start by selecting a fast shutter speed
usually 1/125 of a second or fasterthen use the aperture to adjust the exposure.
Case Study 4: Upper Yosemite Fall RECIPROCITYShutter speed and aperture have a reciprocal relationship. If you reduce the amount of
light coming through the lens (aperture) by one stop, but increase the time the shutter
is open by one stop, the same amount of light will reach the sensor. This means you
can use several different combinations of shutter speed and aperture to get the same
exposure. All of the following combinations will allow an equal amount of light to reach
the sensor:
1/250 at f/2.8
1/125 at f/4
1/60 at f/5.6
1/30 at f/8
1/15 at f/11
1/8 at f/16
1/4 at f/22
Which combination you choose depends on whether you want more depth of field or
less, a faster shutter speed or a slower one.
Usually you should start with the most important setting. If depth of field is more critical
than motion, set the aperture first, then use whatever shutter speed will give you the
right exposure. If either camera or subject movement is a concern, set the shutter speed
first, then dial in the aperture that gives you the exposure you want.
If, however you want the fastest shutter speed possible for the available light, start by
setting the lowest f-stop number on your lens. This wide aperture will pass more light
through the lens, and allow you to use a shorter shutter speed. If you want the slowest
shutter speed possible for the available light, start by setting your highest f-stop number
(and lowest ISO). This small aperture will minimize the light reaching the sensor, and
require a long shutter speed to get the right exposure.
If neither shutter speed nor aperture mattersif the camera is on a tripod, the subject
isnt moving, and the scene has little depthstart by setting a middle f-stop like f/8 or
f/11, as most lenses are sharpest at medium apertures.
B
24
Case Study 5: Wildcat FallBLURRING MOTION
While a fast shutter speed can emphasize the texture
and power of large waterfalls, a slow shutter speed
often works better for small cascades. Photographing
this scene in Yosemite, I wanted to blur the motion
of the water to give it an ethereal look and create
contrast between smooth water and rough rocks.
After finding a nice balanced composition, I put
the camera on a tripod (I wanted the water to be
blurred, not the rocks), then added a polarizing
filter to cut reflections on the wet rocks and make
the white water stand out. Next I selected the
smallest aperture on my 1740mm zoom: f/22.
If I wanted to blur the water, why did I set the aperture
first, rather than the shutter speed? First, there was a
lot of depth herethe rock in the lower-left corner was
only a few feet from the cameraso I needed a small
aperture to get everything in focus. But even if depth
wasnt an issue, when blurring motion I routinely start
with my lowest ISO and smallest aperture, as this will
give me the slowest shutter speed possible for the light-
ing conditions. The less light coming through the lens,
the longer the shutter speed has to be to give you the
right exposure. (Adding a polarizing filter or neutral-
density filter can slow the shutter speed even more if
necessary, as when trying to blur motion in direct sun.)
How slow a shutter speed do you need to blur motion?
That depends on how fast the subject is moving across
the frame. For flowing water, 1/2 a second or slower
will usually give the water that soft, silky appearance.
But sometimes a slightly faster shutter speed, like 1/4 or
1/8, looks better, giving the water a bit more texture.
For this scene, at f/22 with 100 ISO, the meter indicated
a shutter speed of 1.3 seconds, which seemed perfect
nice and slow. I made a test exposure, and the histogram
looked good: near, but not touching, the right edge.
The world is in constant motion, and many situa-
tions can lend themselves to slow shutter speeds.
Ive blurred wind-blown moonlit clouds during
a six-minute exposure, and panned with flying
birds at 1/15th of a second. Use your imagina-
tion, and dont be afraid to experiment.
BLURRING MOTIONCase Study 5: Wildcat Fall
Photograph two different moving subjects, one using a fast shutter speed to
freeze motion, the other with a slow shutter speed to blur the movement.
Its easier to freeze motion in bright light, and easier to blur motion in low
light like shade or dusk. To blur motion, either set the camera on a tripod
and let the subject move through the frame, or try panning, where you
follow the subject with your camera while blurring the background behind
it. Either way, try different shutter speedsevery situation is unique, and
often one speed will be just right.
EXERCISE FREEZE AND BLUR MOTION
26
Case Study 6: Stormy Afternoon at Mono LakePUSHING THE ISO
In some photographs, shutter speed is the most impor-
tant consideration. In other cases, aperture and depth
of field are the biggest concerns. But what if both are
important? What if you need a fast shutter speed and
great depth of field? Then its time to push the ISO.
By raising the ISO you amplify the light signal reaching the
sensor, allowing you to use a faster shutter speed, smaller
aperture, or both. This can be extremely valuable when try-
ing to handhold the camera or freeze motion in low light.
But like many things in photography, and in life, theres a
trade-off: the higher the ISO, the more noise youll get.
However, every year cameras and noise-reduction soft-
ware get better, and its sometimes possible to get amaz-
ing results at high ISOs. To test your cameras limitations,
try shooting with high ISO settings and take a zoomed-in
look at the images on your computer. Better yet, make
some large prints and see how apparent the noise is.
I made this image of Mono Lake with a Canon 1Ds Mark
II, which, as I write this, is a seven-year-old modelan-
cient technology by todays standards. But it has a
full-frame sensor, which helps; in general, the larger the
sensor, the better it handles noise. And noise-reduction
software has improved immenselyIve made virtually
noise-free images with this camera at 1600 ISO.
In this wide-angle composition I figured that f/16 would give me
enough depth of field to keep the foreground waves and distant
tufa towers in focus. At 100 ISO the meter indicated 1/30 of a
second, which was too slowthe waves would be blurred. So I
set the shutter speed to 1/125 of a second,
figuring that would be the minimum speed neces-
sary to freeze the motion. Then I simply pushed
up the ISO until the meter indicated I had the cor-
rect exposure (which happened to be at 400 ISO).
A test exposure showed a perfect histogram, with
the brightest pixels near, but not touching, the
right edge, and no blinkies. That meant I could
leave the settings alone and concentrate on try-
ing to catch the waves in the right position.
With ISO, doubling the number increases
the exposure one stop. So increasing the
ISO from 100 to 200 gained one stop of
extra light sensitivity; pushing the ISO further
to 400 gained another stop, for a total of two stops. That
allowed me to shorten the shutter speed from 1/30 of a
second to 1/125 of a second, a two-stop difference.
But you dont have to calculate this stuffjust do what I did:
set the shutter speed and aperture you want, then increase the
ISO until you get the right exposure. Youll get more noise,
but Id rather have a little noise than a blurry photograph.
PUSHING THE ISOCase Study 6: Stormy Afternoon at Mono Lake
28
Case Study 7: Grey Pines after a SnowstormHIGHLIGHT RECOVERY, AND EXPOSING TO THE RIGHT
Usually you want the brightest pixels to be
near, but not touching, the right edge of
the histogram. This is called exposing to
the right (ETTR for short), as youre trying
to push the histogram as far to the right as
possible without losing highlight detail.
By making the photograph as light as possible,
but not washed out, you get the maximum pos-
sible shadow detail. Also, in a digital file theres
actually less information in lower values, making
those low valuesthe shadowsmore prone to
noise and posterization. So the lighter you make
those shadows, the less noise youre likely to see.
With raw files its often possible to recover seem-
ingly overexposed highlights in software. Because
of that, some ETTR devotees actually suggest
deliberately overexposing your photographs. I
dont recommend that, because even if you can
recover those highlights its sometimes impossible
to make that overexposed image look rightto
give it the appropriate tones, colour, and con-
trast. But that ability to recover overexposed
highlights does give you a bit more latitude,
and, at least with some cameras, allows you to
be less concerned about small areas of blinkies.
Photographing these grey pines in the Sierra
Nevada foothills, with my 70200mm zoom
lens on a tripod, and the ISO set to 100, I di-
aled in an aperture of f/22 (my sharpest f-stop
for that lens), and used the shutter speed the
light meter recommended: 1/20 of a second.
I took one frame, then checked the imageand
saw some blinkies, and a small spike at the right
edge of the histogram (A). I quickly dialed in a
faster shutter speed1/30 of a secondand kept
shooting, but the mist had already shifted, and
it turned out that this first frame was the best.
HIGHLIGHT RECOVERY, AND EXPOSING TO THE RIGHTCase Study 7: Grey Pines after a Snowstorm
A
30
Fortunately it was easy to bring back detail in those washed-out high-
lights with Lightrooms Recovery tool. The zoomed-in view shows
an area of overexposed mist in the upper-right portion of the image
(B). After pushing the Recovery slider to the right (to +17), you can
see detail in this formerly blank area (C). The final image has good
overall contrast, and detail in both highlights and shadows (D) .
With my camera (Canon 1Ds Mark II), I dont worry about
small areas blinking on my LCD screen, as I know these can
be recovered later. But keep in mind that this only works
with raw files, and not with every camera. Try the exercise
on the next page to see if it works with your model.
HIGHLIGHT RECOVERY, AND EXPOSING TO THE RIGHTCase Study 7: Grey Pines after a Snowstorm
B C
D
31
Case Study 7: Grey Pines after a Snowstorm
Find a scene with some white or near-white areas,
like clouds, snow, a white building, or a person
with a white shirt. Make sure that white object is
the brightest thing in the frame (i.e., you dont
want your white subject to be in the shade, while
other areas of the photo are in the sun).
Its best to do this exercise on a tripod, with a still
subject, so that motion isnt an issue. With the
camera set to raw mode, find the theoretically
correct exposure, with the brightest pixels near,
but not touching, the right edge of the histogram,
and no blinkies. Then make an exposure one-third
of a stop brighter by setting a slower shutter
speed. Repeat that five more timesin other
words, increase the exposure by one-third stop
increments six times total, until youve gone
two full stops brighter than the theoretically-
correct exposure.
Download the images and look at them in your
favourite raw-processing software. (It really
helps to be using a good, calibrated monitor!)
First, compare the histograms and highlight
alerts (blinkies) of the images on your camera
to the ones on your monitor. You may find some
differences: an image with a good-looking
histogram on the camera may turn out to be
overexposed when you view it on your computer,
or vice-versa. Knowing these differences can help
you make adjustments in the field.
Next, try using the Recovery or Highlight
Recovery tool in your software on some of the
overexposed images. Zoom in on the
washed-out areas and see if youre actually
recovering detail and texture, or just making
these areas look grey. Also, look for uneven,
blotchy tones in the highlights.
With most modern DSLRs youll probably find
that you can recover detail in highlights that are
as much as a stop overexposedperhaps even
more. But with some cameras the limits may
be less. Or you might find that you can recover
detail, but you see abrupt transitionsthat
blotchy look I mentioned.
Armed with this new knowledge you may become
less concerned about small, overexposed areas
in your photographsor you could realize that
you have to be really careful to not overexpose
anything. But either way, youll know.
So far Ive just talked about the overall histogramthe
luminance histogram. But most cameras also have the
ability to display histograms for the red, green, and
blue colour channels separately.
Do you need this? In most cases, no. But sometimes,
when photographing a sunset sky, red or yellow
flowers, or any highly-saturated colours, one of the
colour channels will be overexposed, and you wont
see that in the luminance histogram, nor will the
blinkies warn you about it.
Overexposing one channel could make some colourful
highlights look blotchy, or lack detail. With raw files
you may be able to recover this detail, but you may
notit depends on the camera, and how overexposed
that channel is. So when photographing colourful
subjects, its a good idea to look at the RGB histogram,
and if one of the channels shows a spike on the right
side, make a darker exposure.
EXERCISE TEST THE LIMITS OF HIGHLIGHT RECOVERY
RGB HISTOGRAMSAn RGB histogram showing an
overexposed red channel, with
a spike at the right edge.
Case Study 8: Oaks and Mist, AutumnINCLUDING THE SUN IN THE FRAME
I usually dont want any part of a photograph to be overexposed.
We never see washed-out highlights in real life, and it looks unnat-
ural to see them in a photograph. But theres one major exception:
you cant see detail in the sun itself, because its too bright. In fact,
if you stare at it too long youll damage your eyes! So when you
include the sun in a photograph, or sunlight reflecting off water
or glass, it seems perfectly normal for these areas to lack detail.
The sun shining through the mist from behind these oak
trees was beautiful, but the contrast was extreme, and I
had to avoid lens flarethe distracting coloured spots
created when the sun hits the front of your lens.
In situations like this I try to get just the edge of the sun poking
out from behind a branch or trunk. This makes the bright sun a
focal point, but blocks the flare. So I positioned my camera (on a
tripod of course) so that the sun was hidden behind a tree branch,
figuring that the sun would edge into view by the time I was ready.
I set the aperture to f/16, which seemed sufficient to get both
the yellow foreground plants and trees in focus. Small apertures
also create a starburst effect when you include the sun in the
frame. At 100 ISO I dialed my shutter speed to the meters rec-
ommendation, 1/60 of a second, and made a test exposure.
INCLUDING THE SUN IN THE FRAMECase Study 8: Oaks and Mist, Autumn
A
34
Unfortunately the histogram didnt help much, since theres
bound to be a spike at the right edge from the sun and adjacent
areas. In these situations I judge the exposure by the amount
of blinkies. A small amount of blinkies in and around the sun
is fine. More than that, and the image is probably overexposed.
If just the sun itself is blinking, its probably underexposed.
My test exposure showed a small amount of blink-
ies around the sun, so this seemed right. But to hedge
my bets I set the camera to auto bracket three exposures:
the middle, or base exposure (1/60 of a second), plus one
stop lighter and one stop darker (1/30 and 1/125).
Now I almost hesitate to mention bracketing, as some people
will take this as a license to be sloppy with their exposures
and just bracket the heck out of every scene. But wild bracket-
ing doesnt work with moving subjectsyou have to get the
exposure right at the instant the subject is in the perfect posi-
tion. And even with static subjects, mindless bracketing may
not be enough: you could bracket one stop lighter and one
stop darker than the meter recommends, when the right expo-
sure is actually three stops darker than the meter suggests.
INCLUDING THE SUN IN THE FRAMECase Study 8: Oaks and Mist, Autumn
B
35
But in difficult situations, intelligent bracketing can help.
By intelligent I mean that you use the histogram and blink-
ies to help you make the best exposure you can, but hedge
your bets by making lighter and darker exposures as well.
With this scene I knew that my test exposure (1/60 at f/16) was
close, and by making exposures one stop light and darker I would
be sure to get it right. When the sun edged out from the behind
the branch I bracketed three quick exposuresclick click click.
The middle exposure turned out to be the best (A Page
34). Small areas in and around the sun are washed out, but
that seems normal and natural, and the rest of the tones
in the photograph look about right. Most importantly, the
sunbeams cutting through the fog stand out clearly.
The lighter exposure looks washed out (B Previous
Page), while the darker one seems murky (C). The blink-
ies cover too large an area in the lighter version, and are
barely visible in the darker one. Again, the middle expo-
sure, with some blinkies, but not too many, seems best.
So when the sun is in the frame, its okay to see some
washed-out areasas long as theyre not too big.
INCLUDING THE SUN IN THE FRAMECase Study 8: Oaks and Mist, Autumn
C
36
Case Study 9: Unicorn PeakSPOT METERING AND THE ZONE SYSTEM
With film, the Zone System is the best way
to get accurate exposures in a wide variety of
situations. With a digital camera, where you
can check the exposure with the histogram,
the Zone System is less essential. But the ex-
posure methods Ive described so far involve
some trial and error; the Zone System will
lead you to the perfect exposure more quickly.
With practice you should get it right on your
first try at least 90 percent of the time.
Volumes have been written about the Zone
System, but Im going to describe a simple
method of applying the Zone System to
digital capture in just a couple of pages.
First, while Ansel Adams and Fred Archers
original Zone System had eleven zones, zero
through ten, were going to concentrate on
just the middle ones, three through seven.
Zone 5 represents a mid-tone in the scene.
Anything one stop darker is zone 4, two stops
darker zone 3, and so on. Anything one stop
lighter is zone 6, two stops lighter zone 7, etc.
Zones 3 and 7 are important because they
represent the limits of most digital cameras.
Zone 2 is too dark to show detailessentially
black. Zone 8 is too light to show good de-
tailwashed out. So Zones 3 and 7 are the
lower and upper limits for retaining detail
and texture (though cameras vary, and some
high-end models may go beyond this).
SPOT METERING AND THE ZONE SYSTEMCase Study 9: Unicorn Peak
Zone 2
A hint of detail.
Zone 3
Dark, with good detail.
Zone 4
Dark tone or colour.
Zone 5
Middle tone,
medium colour.
Zone 6
Light tone or
pastel colour.
Zone 7
Light, with texture.
Zone 8
A hint of detail,
but essentially
washed out.
38
Okay, enough backgroundhow do you use it? The
simplest approach to the Zone System concentrates
on highlights and ignores shadows. Start by picking
the most important highlight. Whats important? Not
a tiny spot, and not something that lacks detail, like
a blank sky. Pick the brightest significant part of the
photograph that needs to have detail and texture.
In this scene from Yosemites high country, the
brightest significant highlights were the cloud at
the top of the frame and the patch of white wa-
ter near the lower-left corner. I thought the cloud
was slightly brighter, so I spot-metered that.
When using the Zone System, make sure the whole
spot is filled with a consistent toneyou dont
want a mixture of light and dark areas. A narrow-
angle spot meter is invaluable. In this case, I pushed
my 70200mm zoom out to 200mm and pointed
the central spot at the brightest part of the cloud.
At 50 ISO, with my aperture set to f/22 (I used my
lowest ISO and smallest aperture to make the shut-
ter speed as slow as possible), the spot-meter read-
ing from the cloud indicated 1/30 of a second.
If you remember, back in the beginning of this eBook
I said that all light meters are calibrated to a middle
tone, or middle grey. If I took this photo at the meter
reading (1/30 at f/22) the cloud would look grey, not
white. This is why spot meters are tricky. You cant
just point the meter at something and trust your read-
ing. You have to know whether the spot is pointed at
a middle tone, or something lighter or darker. In this
case I metered a highlight, so it shouldnt be zone
5, a middle toneit should be lighter than that.
So, with my spot meter still pointed at the cloud, I ad-
justed the shutter speed until my exposure scale showed
that the cloud was two stops overexposed: +2 on the
scale (A). This placed the cloud on zone 7. Zone 8
would be washed out, so zone 7, two stops lighter than
a middle tone, was as light as this cloud could get with-
out losing detail. The resulting shutter speed was 1/8
of a second, two stops slower (and therefore brighter)
than the initial meter reading of 1/30 of a second.
A
SPOT METERING AND THE ZONE SYSTEMCase Study 9: Unicorn Peak
39
next step was very importantI didnt touch
anything! Id already set the exposure, so I left the
shutter speed and aperture alone, zoomed out to
70mm, re-composed, and took the picture. The
histogram looked just right, with the brightest pix-
els near, but not touching, the right edge (B).
For most photographs you can do exactly the same
thing: spot-meter the brightest important highlight in
the scene, then overexpose that area by two stops to
place it on zone 7. This will push the brightest pixels
in the image near, but not touching, the right edge
of the histogram. (Of course you should always check
the histogram and adjust the exposure if necessary.)
This procedure might seem complicated, but it
only took me about five seconds. I just pointed
my spot meter at the cloud, turned the shut-
ter speed dial until the exposure scale indicated
+2, then recomposed and took the picture.
Sometimes you may not want the brightest impor-
tant highlight to be at zone 7, or +2 on the exposure
scale. Zone 6 or 6 1/2 (+1 or +1.5) might be better if
that highlight has saturated coloursa sunset cloud,
for example, or maybe yellow autumn leaves.
One more thing: why didnt I just spot-meter a mid-
dle tone, like the rocks? That might work, but what if
the cloud was three or four stops brighter than those
rocks? Then the cloud would be zone 8 or 9, and washed
out. By metering the brightest important highlight
Im going directly to the most vital area of the pho-
tograph and adjusting that to the desired exposure.
B
SPOT METERING AND THE ZONE SYSTEMCase Study 9: Unicorn Peak
40
Case Study 10: Sun Breaking Through Mist, Tuolumne MeadowsHDR AND EXPOSURE BLENDING
Every digital camera has a fixed dynamic range. If a
scenes contrast exceeds that range, then no matter
how you expose the photograph youll end up with
black shadows, washed-out highlights, or both.
That is, unless you combine two or more exposures.
With HDR, or high-dynamic range photography,
you can capture several different exposures of the
same scene, then blend these images together in
software, retaining both highlight and shadow
detail even in scenes with extreme contrast.
These exposures can be combined manually in
Photoshop, with HDR software like Photomatix Pro
or Nik HDR Efex, or with other exposure-blending
software, like my current favourite, LR/Enfuse.
A tutorial on using these applications is beyond
the scope of this book. But before you can at-
tempt to blend exposures in software, you need to
capture the necessary information in the field.
HDR AND EXPOSURE BLENDING
Case Study 10: Sun Breaking Through Mist, Tuolumne Meadows
A
42
Photographing the sun breaking through morn-
ing mist in Tuolumne Meadows, in Yosemites high
country, I could see that the contrast was extreme,
and I knew the only way to capture this scene was
to blend several different exposures together.
I started the way I always do, by finding the right expo-
sure for the highlights, with the brightest pixels near,
but not touching, the right edge of the histogram. In
this case, I figured that blinkies in the sun itself would
be okay, but I didnt want the clouds next to the sun to
be overexposed. At f/22, 100 ISO, the best exposure for
the highlights turned out to be 1/250 of a second (this
was actually two stops darker than the meter reading).
But at this setting the shadows looked inky, and there
was a large spike at the left edge of the histogram, indi-
cating black, detail-less shadows. I guessed that two more
exposuresone a stop lighter, another two stops light-
erwould give me enough shadow detail, and the infor-
mation I needed to blend these images together later.
HDR AND EXPOSURE BLENDING
Case Study 10: Sun Breaking Through Mist, Tuolumne Meadows
B
43
I could have simply moved my shutter speed dial three clicks
to the left (to 1/125 of a second) and made a second exposure,
then turned the dial three more clicks to the left (to 1/60 of
a second) and made the third exposure. But the clouds were
moving, and any movement between frames would make it
difficult to blend the images together later. So I set my camera
to auto bracket three exposures at one-stop increments. Then
I moved my shutter-speed dial to the middle exposure, 1/125
of a second, and fired off three quick imagesclick click click.
Like most cameras, mine auto brackets on either side of
the exposure Ive set. So by starting at the middle expo-
sure of 1/125 of a second, it made another exposure at
1/250 (perfect for the highlights), then a third at 1/60
(good for shadow detail)exactly what I wanted.
The darkest image (1/250) showed the brightest pixels
near, but not touching, the right edge of the histogram,
and only small blinkies in the sun itself, but the shad-
ows, as expected, were black (A page 44). The middle
exposure showed a spike at the right edge, but nothing
pushed up against the left edgein other words, it had
shadow detail, at least theoretically (B previous page).
HDR AND EXPOSURE BLENDING
Case Study 10: Sun Breaking Through Mist, Tuolumne Meadows
C
44
The lightest exposure showed a big spike at the right edge,
but a nice gap between the darkest pixels and the left edge,
ensuring that I had noise-free shadows (C previous page). So
I had one image with good highlight detail, one image with
good shadow detail, and one in betweenjust what I wanted.
I blended the three images together with LR/Enfuse, which
usually creates more natural-looking results than true HDR
software like Photomatix. Then I applied finishing touches
in Photoshop (D). This final version has good shadow and
highlight detail, and renders the scene as I visualized it.
To recap: when youre trying to capture a series of exposures,
with the intention of blending them together later, start by
finding the right exposure for the highlights (with pixels near,
but not touching, the right edge of the histogram). Then make
an exposure one stop lighter, then one stop lighter again, and
so on until you see a gap between the darkest pixels and the
left edge of the histogram, showing that you have shadow detail.
If the scene contains clouds or other moving objects, first,
again, find the right exposure for the highlights. Then set your
camera to auto bracket three exposures at one-stop intervals.
Next, move your shutter-speed dial three clicks, to the mid-
dle exposure of the sequence, and fire off three frames.
Use a tripod to ensure that the images line up properly. If youre
using JPEG mode, set the white balance manually; with the
camera set to automatic white balance the colour could change
between exposures, making it harder to combine the images
later. With raw mode, automatic white balance is fine, as you
can sync the colour temperature between the images in software.
HDR AND EXPOSURE BLENDING
Case Study 10: Sun Breaking Through Mist, Tuolumne Meadows
D
45
Conclusion:TECHNIQUE AND VISION
I hope the preceding pages have helped you gain a better
understanding of exposure and the fundamental photo-
graphic toolsshutter speed and aperture. But getting good
exposures is not an end in itself, but rather a means to an
enda way of helping you make better photographs.
What defines a good photograph for one person might
be different than for another. We could talk about light,
composition, or technical proficiency, but I think that if we
dig down, what most of us are trying to do is communicate
something about the place or subject were photographing.
Were trying to capture a mood or a feelingto express
ourselves in some way, and evoke a reaction in the viewer.
Exposure, then, is just a tool for communication.
Theres no such thing as a correct exposure for any
situation. If the exposure helps you say what youre try-
ing to say, then its correct enough. If it detracts from
your message, then it isnt correctat least for you,
in that instance. Exposure must always serve your vi-
sionnot someone elses, nor some arbitrary ideal.
These last four photographs deviate from the accepted
standards for proper exposure and sharp detail. Instead,
I made choices that, to me, conveyed a feeling or mood
that fit the subject. A lighter exposure communicates a
different mood than a darker one. Sharpness conveys
a different feeling than deliberate blurring. So use your
tools well. Rather than striving for technical perfec-
tion, use technique to make more expressive images.
Conclusion:TECHNIQUE AND VISION
(Left) To capture the soft, delicate quality of this iris, I overexposed the image slightly, and used a wide-open
aperture to throw most of the flower out of focus and create washes of colour.
(Previous page) Here I went in the other direction and deliberately underexposed this photograph of Half Dome,
creating large areas of pure black, and enhancing the stormy mood.
47
This photograph of a Jeffrey pine was deliberately and drastically overexposed to let the highlights wash out to create a delicate, high-key look.48
To convey the beauty and coordinated motion of these snow geese, I used a slow shutter speed (1/15th of a second) while panning as they took flight.49
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