depth of field workshop
TRANSCRIPT
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7/27/2019 Depth of Field Workshop
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(represented by a low f-stop number like
f/2.8 or f/4) to a narrow aperture (with a h
number, such as f/22 and f/32). The choic
of aperture is key to controlling exposure,
wide apertures let in more light and narrow
apertures let in less, and it also has a big
bearing on depth of field, with wide apertureducing it and narrower ones increasing
Distance and focal lengthWhen it comes to selecting an aperture yo
also need to consider your distance from t
subject, as the closer you are the shallowe
the depth of field will be when youre
focusing close-up and using a wide apertu
the depth of field may only measure a few
millimetres. Imagine, for instance, that yo
using a 70mm lens on a 7D to photograph
Depth of field, or DoF for short, is
the distance between the nearest
and farthest objects in a scene
t appear acceptably sharp in a photo.
say acceptably sharp because only
e point will be truly razor-sharp in your
tures, as your lens can only focus at a
gle distance. However, the sharpness
s off gradually both in front of and
hind the point youre focusing on, anddepth of field is a measure of how far
s sharp area extends. Controlling the
pth of field makes a real difference to
w your pictures look. The less depth
eld there is, the easier it is to blur
ckgrounds, which is often desirable
portraits. Increasing the depth of field
helps you to capture more detail in a subject
or scene, and youll generally want as much
depth of field as you can get when shooting
landscapes and macro subjects.
Your camera doesnt have a depth of
field control as such; rather its governed by
a number of factors and camera settings.The distance to the subject (and the distance
between subject and background), the focal
length of the lens and the size of the cameras
sensor all play a part, although its the choice
of aperture thats generally seen as having
the biggest impact.
For those new to photography, the
aperture is the hole in the lens that light
has to pass through to reach the cameras
imaging sensor. Its measured in f-stops,
and can be adjusted from a wide aperture
You generallywant as muchdepth of fields you can get
when shooting
andscapes
epth of field is anndispensable creativeool but whatxactly is it, and how
an you control it?
Whats depth of field all aboutUseLiveViewtohelpyo
judgefocusinganddeptoffieldaccurately
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7/27/2019 Depth of Field Workshop
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EPBYSTEP
et the apertureFor maximum sharpness
youll need to use relatively
arrow apertures. Select
perture Priority and set an
perture of around f/16 (higher
stops can lead to soft pictures).
se this technique to get the maximum depth of field possible when shooting landscapes
How to use hyperfocal focusing
ect one metre away. With a wide aperture
2.8, the depth of field may only be 2cm at
close distance. However, if the lens was
cused on a subject 10 metres away, that
e aperture may give a depth of field of
ost 170cm. Consequently, your focusing
ds to be bang-on when you use extremely
e apertures at close distances, otherwise
ortant details may look soft.
efore you set the optimum aperture
position yourself at the perfect distance
to provide the depth of field you want for a
shot, you need to think about the best focal
length to use. The lens doesnt affect the
depth of field per se when it comes to
aperture selection, f/5.6 on a 20mm lens
offers the same depth of field as f/5.6 on a
200mm lens but the magnification offered
by the focal length does play a part. Longer
lenses have a narrower field of view than
wider ones, so they take in less of a scene,
effectively making everything appear bigger
in the frame. This includes the backg
with any blur becoming magnified to
Sensor size has a similar effect on
depth of field. The larger the imaging
inside the camera is, the easier it is t
shallow depth of field effects this is
the reasons many pros reach for full
cameras. The smaller APS-C sensor
find in the majority of EOS bodies rec
smaller area of the image projected
lens, so everything appears larger in
Turn off autofocusSwitch your lens to the
manual focus setting:
you need to set the lens at a
precise distance with hyperfocal
focusing, and the lens would
refocus if left in AF mode.
Find the distanceVisit www.dofmaster.com
(or use its smartphone
app) and input your camera and
lens info. Youll be given a table of
depth of field measurements and
a hyperfocal distance setting.
Set the distanceFocus the lens at the
distance suggested
the aperture being used. I
image appears blurred, us
cameras depth of field pr
button to show the true pi
Wide apertures reduce the depth of
eld and help to separate the focal
oint from the rest of the picture,
whereas narrow apertures bring more
f a scene into apparent sharp focus.
Although apertures are consistent
cross lenses (an aperture of f/8 has
he same effect whether its used on a0mm lens or a 500mm lens), lenses
ont offer the same range of settings.
or instance, expensive fast lenses
ffer very large maximum apertures for
heir focal lengths, such as f/2.8 on a
rofessional 300mm lens, compared to
/5.6 on a cheaper equivalent. As well
s letting more light in (and enabling the
aster shutter speeds that give them
heir name), faster lenses enable you
o capture a shallower depth of field.
How aperture affects depth of field
f/16
Narrow aperture:
f/2.8Wide aperture: f/2
A wide aperture offers a
band of sharpness. Both
up and distant backgrou
details will disappear int
Such a shallow depth of
demands accurate focu
here, the mallard has moits head, so its no longe
Choosing a narrow aper
extends the depth of fiel
this can be more forgivin
it comes to focusing erro
Narrow apertures can re
slower shutter speeds
blurred pictures caused
camera shake, as seen h
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7/27/2019 Depth of Field Workshop
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For landscape photography, or any other situation
that requires an extended depth of field to keep
everything sharp from the foreground to the
background, youll want to use narrow apertures.
However, as weve seen this leads to slower
shutter speeds; this is no problem if youreshooting with a tripod, but if youre shooting
handheld sharpness can be lost through camera
shake. The solution here is to increase the ISO to
compensate. First, set the aperture, then set an
SO that brings the shutter speed within the safe
handheld shooting speed of the lens (aim for
1/focal length, so 1/50 sec for a 50mm lens).
Up the ISO toget more DoF
Although wide apertures reduce the
depth of field, the effect depends on
how far the subject is from the lens.
The farther away the subject is, the
greater the depth of field even when
a lens is used at its widest aperture.
Take these two examples: both were
shot at f/2.8, but at different distances
from the subject. The shot of the goose
doesnt work because the background
still looks comparatively sharp, and thebird blends into it. The dandelion image
is more successful: the close focusing
and wide aperture combine to produce
a shallow depth of field that separates
the flower from its surroundings.
Why distancematters
Previewing depth of field
Pressing the depth of field button accurately
previews the DoF at the selected aperture of f/11
1/160 secatf/4; ISO200
A wide aperture of f/4 means the
extreme foreground and backgroun
detail appears out of focus
The bright view provided by the wide-
open aperture of f/2.8 in Live View
s difficult to gauge the depth of fieldwhen looking through the viewfinder, as
he image you see is shown at the lenss
widest aperture setting; the aperture
ouve dialled in isnt actually set until just
efore the exposure is made. Most EOS
D-SLRs have a depth of field preview
utton, which youll find near the lens
mount: holding this down sets the lens tothe selected aperture, so you can gauge
what will be sharp; the downside is that the
narrower the aperture, the darker the
image in the viewfinder. The alternative is
to use Live View mode: if you hold down
the depth of field button the bright image
on the LCD will enable you to judge the
depth of field accurately, even when using
narrow apertures in low-light conditions.
f/2.8: focusing at 20ft
f/2.8:focusingat1ft
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7/27/2019 Depth of Field Workshop
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1/50secatf/16;ISO1600
Its better to choose a narrow
aperture, then increase the ISO to
enable a safe handheld shutter speed
Fisheye lenses5hintsandtipsfor
1 Choose your viewFisheyes generally come in
two flavours: full-frame or
circular. The effect depends
on the lens design and the
size of the sensor inside the
camera, so check the specs
to make sure the results will
be what youre expecting.
3 Exposure issuesThe inclusion of such a
wide expanse of scenery
can cause severe contrast
problems if you have a
bright sky and a darker
foreground. You may need
to shoot several bracketed
exposures, and combine the
images in post-processing.
5 Try before yoWant to have some
fun without having t
splash out? The am
Canon EF 8-15mm f
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2 Get closeBecause of the incredibly
wide view of a fisheye lens
(up to 180 degrees, corner
to corner), youll need to get
much closer to a subject
than would ordinarily be
the case in order to prevent
it from looking too small inthe picture.
4 Check the edgesIts all too easy for your feet
or your shadow, or a set of
tripod legs, to appear in
the bottom of the picture in
fisheye shots. Make a quick
check of the edges of the
frame before you press the
shutter button.
picture than it does using the same focal
ength on a full-frame camera; its a bitike cropping the shot in Photoshop.
Attach a 50mm lens to an APS-C D-SLR
ike the 700D, for instance, and its
effective view will be the same as that of
an 80mm lens (50mm x 1.6 crop factor
of the smaller sensor). On a full-frame
camera such as the 6D, theres no crop
factor it captures the full view of the
ens. In order to get the same image size
as on the 700D, youd need to be closer
to the subject, and, as weve seen, the
closer you are to a subject the shallower
the depth of field becomes.Of course, cameras with smaller
sensors can be useful if youre looking
to maximise the depth of field in your
shots, and a technique called hyperfocal
focusing will also help you to maximise
front-to-back sharpness in a scene.
This involves manually focusing the
lens at a distance that will capture sharp
detail from half the hyperfocal distance
to infinity see our step-by-step
walkthrough on page 71. Q
Each month we highlight a Canon EOS D-SLR or type of lens
and provide handy advice to help you get more from your gear
In association with...
SpecialistlensesThe problem with using very n
apertures to extend the depth
is that it can reduce sharpnes
a phenomenon called diffract
wider aperture will produce a
image but with less DoF, so yo
to decide which is more impor
or set an aperture somewhere
middle. Not so if you use a tilt-
lens: these pricey chunks of g
enable you to use a wide aper
maximum sharpness, and the
lens to adjust the plane of focu
maximise the depth of field.
I