Exposing with a flash!
description
Transcript of Exposing with a flash!
Happy Bokeh Press
Saul McKeon
a how-to guide for mastering exposure when using off camera hot shoe flash
Exposing with a flash!
Photographer’s Workshop Series
First published in 2012 in England by
Happy Bokeh Press
Copyright © 2012 Happy Bokeh Press
Happy Bokeh Press is an imprint of
Johnson McKeon LtdFifth FloorHorton HouseExchange FlagsLiverpoolL2 3PFEngland
www.johnsonmckeon.com
All titles in the Photographer’s Workshop Series are available directly from Happy Bokeh Press, as well as from all good retailers.
British Library Cataloguing in Publication Data.A catalogue record for this book is available from the British Library.
ISBN 978-1-909320-00-0 (print)
ISBN 978-1-909320-01-7 (e-book)
All rights reserved by the publisher.
Welcome 1
How fl ash light affects exposure 3
How fl ash position affects exposure 13
How fl ash modifi ers affect exposure 19
And fi nally... 24
CONTENTS
1Saul McKeon
Aim of this workshop
Today we are going to take the fi rst few strides of our ex-
ploration into fl ash photography. This journey begins by
mastering how to expose correctly for fl ash. Once we have
done that, we will take a quick look at how changing the
position of the fl ash unit affects the fi nal image. We will end
by looking at how fl ash modifi ers—such as snoots, grids and
gels—affect the exposure.
Once you are confi dent with setting and judging exposure
for a single fl ash unit, you are heartily encouraged to join
us in our follow-on workshops that fi rther explore the use of
fl ash lighting to enhance modelling, mood and atmosphere.
Welcome
Target audience
» Do you restrict fl ash to low light situations?
» Are you unsure how to expose properly for fl ash, so
tend to leave everything set to automatic?
» Do you feel you are not getting the most out of your
fl ash unit?
» Do you just want someone to take you by the hand and
show you how to use fl ash confi dently?
If you relate to any of the above, we suggest you read on!
Through the Photographer’s Workshop Series, we focus on
exploring how to master one aspect of photography at a
time, which:
» allows each guide to be concisely written and tightly
focused upon its particular topic, making it ideal for
busy people,
» enables enthusiasts to build up their knowledge and
skills at their own pace,
» caters for experienced photographers who can reach
straight for the guide they need to quickly fi ll a gap in
their skill set.
2
Essential equipmentSLR Camera. We are using our trusty old Can-
on EOS 30D Digital SLR, fi tted with a Canon EFS
17-55mm f2.8 lens. You can pick up this kind of
quality kit second-hand for a small fraction of what
we paid for it a few years ago.
Camera tripod. You will need to keep the camera
in the same position relative to the subject while you
experiment with exposure. Anything sturdy will do.
We are using mid-range Manfrotto 055XPROB legs.
Off camera fl ash unit (ideally TTL-capable). We
are using a mid-range Canon Speedlite 430EX, con-
nected to the EOS 30D by a TTL fl ash cord. Once
you take the fl ash unit off the top of the camera,
you will need to mount it on something. The Canon
Speedlites come with a mini plastic foot for the fl ash
unit if you do not have access to a light stand.
Optional equipmentLight stand. We like the value for money lighting
accessories from Interfi t—though there are plenty of
others—and here we are using their COR751 stand.
Flash modifi ers. We play with Honl snoots, grids
and gels that quickly fasten to the fl ash head using a
velcro system. Great quality and portability in our
view—though again there are plenty of alternatives.
Remote shutter release. We use a Canon Timer
Remote Control (TC-80N3), because we have one
knocking around and it is easier than pressing the
button on the tripod-mounted camera. Any elec-
tronic remote shutter release (otherwise known as
cable release) will help you take sharp photos on
your tripod.
Prior knowledge
Before we begin, you should be comfortable with the basic
concepts of photography.
» You need to understand how to set the aperture and
shutter speed on your camera to produce the exposure
you want.
» You should also know how setting the aperture affects
‘depth of fi eld’.
If not, then no problem, fi rst ‘attend’ the workshop enti-
tled Now turn it off automatic! and then come back here
when you are ready.
Also, if you are unsure how to switch your fl ash unit’s me-
tering mode to manual (i.e. how to turn TTL off if you have
it) and how to zoom the fl ash head (if it can be zoomed),
you will need to refer to the manual for your fl ash unit.
Gear you will need
As the whole point of these workshops is to learn by do-
ing, you will need some basic photographic kit—see right
for what we used. Note that when we mention a particular
brand of equipment it is merely for reference, not because
we urge you to go out and buy the very same model! We
aim to keep kit lists to a minimum in our workshops, making
suggestions for other equipment you may fi nd helpful if you
can easily get hold of it; but no problem if you can’t.
Please bear in mind you do not need expensive equipment
to learn photography. By all means invest in decent kit on
which you can build—such as quality fl ash units and light
stands—but you do not need to use the latest top-of-the-
range camera; we certainly didn’t, so there!
3
How fl ash light affects exposure
4
Photo 3: f2.8 1/15s flash 1/8 powerPhoto 2: f2.8 1/15s no flashPhoto 1: f2.8 1/20s no flash
Hey... what happened there!?
The fl ash was positioned on the mini-
stand that came with it, around 1/4m
from the subject and to the camera’s left.
In keeping with this workshop, we had
switched the fl ash onto manual (i.e.
turned TTL off) and set the power our-
selves. We had also manually zoomed the
lens to 105mm. (See the next page if you
are not sure what all this means!)
The fl ash was clearly far too power-
ful even at just an eighth of full power.
Hmm?
Fortunately, this is where fl ash comes in.
So let’s attach a fl ash, switch it on and see
if we can enhance the light and shadow
on the subject.
Light and shadow work
together to make an object
look three dimensional—
which means shadow is as
important as light!key learning point!
Bumping up the exposure a mere 1/3 of
a notch brightens the picture—note how
we highlight in bold any change in expo-
sure settings from the previous photo.
However, this has resulted in a loss of
shadow detail in the petals.
A jug of fl owers on the kitchen table has
gracefully volunteered its modelling ser-
vices for this workshop.
Let us start by trying to get a good shot in
natural light—that is, without fl ash.
We begin by switching the camera to
manual mode, selecting a wide aperture
for a shallow depth of fi eld and setting
the shutter speed to that suggested by
the camera’s in-built meter. (If you do
not understand this, we recommend fi rst
looking at Now turn it off automatic! )
The resulting shot (above) is not bad—
though perhaps a bit dim?
5
Photo 5: f8 1/15s flash 1/64 power
Photo 4: f2.8 1/15s flash 1/64 power
Zooming a fl ash
Some fl ash heads can be zoomed like a
camera’s zoom lens: focusing or spreading a
given amount of fl ash light. For this work-
shop we manually zoomed the fl ash head in
to its maximum—105mm for the 430EX—
which means the fl ash is at its most direc-
tional and intense.
Note the edges of a photo are likely to be
darker—vignetted—if an on camera fl ash
unit’s zoom setting exceeds the focal length
of the camera lens. This is because the fl ash
spreads out less than the lens ‘sees’.
Much better. But what has happened to the
background? Even if we like the dark back-
ground, it is our duty to fi nd out why it hap-
pened—especially given most indoor snaps of
people resemble this kind of shot!
When we turn the fl ash power down to its lowest
setting (see bottom right), we fi nd it is still too
powerful! So what can we do to prevent overex-
posure? Well we could move the fl ash unit fur-
ther away (see later), or we could zoom out the
fl ash head (see bottom left). However something
else we can do without touching the fl ash unit at
all is to narrow the camera aperture to let less of
the burst of fl ash light through the lens...
Flash power
Perhaps a bit misleading, as most fl ash units
can only fi re at a given fi xed intensity: where
its ‘power’ setting really refers to the dura-
tion of its fl ash. A fraction of 1/1 represents
the longest a given unit can sustain its burst
of fl ash and—in the case of the 430EX—
the shortest is limited to 1/64 of that period.
This means a given fl ash power setting
(e.g. 1/64) would put out more light on a
more powerful fl ash unit—such as a Can-
on 580EX or Nikon SB900—than on our
430EX: as power is relative to the unit itself.
11
Photo 15: f5.6 1/250s auto-TTL flash
So, this time our fl ash exposure is simply a little ‘fi ll-in fl ash’ on the
candle (from camera right). Importantly, it is this understated fi ll-in
fl ash that has given us the artistic licence to reduce both the exposure
of the fl ame and the background without underexposing the candle.
Flash opens up the opportunity to be more creative—it gives us two exposures to play with!creative—it gives us two exposures to play with!
Somewhat paradoxically, fl ash allows
us to create darker photographs!
Now, while we could easily have experimented with getting the right
fl ash exposure by adjusting the fl ash power manually, here we let the
camera have a go by switching the fl ash unit to TTL mode. Not a
bad job EOS 30D, well done.
Note: if you don’t like the bright refl ection of the fl ash on the right of
the candle, fi nd time to join us in the workshop The studio look...
in a fl ash! where we explore the options for this sort of situation in
more detail.
17
Photo 27: automatic exposure, with off camera TTL flash to subject’s left with -1 flash exposure compensation
Most modern cameras and TTL fl ash units have a ‘fl ash exposure compensation’ feature, allowing us to override the automatic TTL fl ash expo-
sure up or down a few notches. Here we dialled in some fl ash compensation on the camera, so that we didn’t have to play around with the fl ash
unit and risk losing the model’s attention.
By instructing the camera to reduce the fl ash exposure by one notch—the camera will narrow the aperture and/or reduce the fl ash power as it sees
fi t—we get a much softer effect. Check your camera and fl ash manuals to see if you have this feature—it is very handy at social events!
24
natural light
fl ash light
And fi nally...At one end of the continuum are the photographers who insist upon
faithfully recording a scene using only natural light. At the other ex-
treme we have photographers who prefer to add their own interpreta-
tion to a photograph through extensive digital image post-processing.
Neither is the correct approach (and neither is wrong); it simply de-
pends upon what sort of photographer you want to be. The use of
fl ash in photography falls somewhere on this continuum. While some
photographers believe it is ‘dishonest’ to use ‘unnatural’ light, others
believe it lifts the craft from mere record-taking to that of an art form.
We fall into the latter camp. You decide where you stand for yourself.
We began this workshop by taking a photograph of a vase of fl owers
in natural light. We then proceeded to explain how fl ash can be used
to add depth, texture and interest to a subject. We explained how to
expose properly for fl ash, how to add depth and texture by moving the
fl ash unit, and how to use modifi ers to change the nature of the fl ash
light itself. So is fl ash photography right for you?
In the same way some artists strive for realism through a ‘chocolate
box’ approach to painting while others insist true art requires the art-
ist to add something of themselves to a scene, photographers also
have different attitudes toward their craft.