Photo Plus - UK (2020-09)

DIGITAL EOS

ESSENTIALS

In this edition of Digital EOS Essentials we explain all you

need to know to capture more consistent exposures

CANONSCHOOL

62 http://www.digitalcameraworld.com

MARCUS HAWKINS

PHOTO EXPERT

Marcus has been passionate about

photography for more than 25

years. A former editor of our sister

publication Digital Camera, he has

written about photography and

cameras for a wide range of clients,

including Canon and Jessops, and

uses a Canon EOS 5 D Mk III.

rying to achieve a

good exposure with

a digital camera is

world away from the

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crossing that came with

VKRRWLQJÀOPBeing able to

preview the results on the rear

screen and check the

brightness range with the

histogram means that you

know exactly what you’re

getting straight out of the

camera, and can make any

exposure adjustment to ensure

you get good results.

And you will need to make

exposure adjustments. Despite

a top-of-the-range EOS body,

such as the 5D Mark IV being

loaded with a 150,000-pixel

metering sensor that can

recognize colour and faces as

well as brightness – it is, in

effect, a miniature imaging

sensor – it can still get things

wrong occasionally.

Rather than measuring the

light that’s falling onto the

subject of a photograph, your

camera measures the light

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into the lens, and this can lead

to exposure errors. Camera

meters are tuned to

approximately 18% grey

• they assume that the world
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  approximately 12-18% of the
  light that falls on it. Although
  many scenes average out to an
  overall mid-tone, there will be
  plenty that are either darker
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  the light that falls on them), or
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  than 18%). Generally
  speaking, your camera still

wants to make an exposure

closer to mid-tone, which can

result in dark scenes looking

too bright and bright scenes

looking too dark.

If the scene or subject is

bright, then you’ll need to add

more light to keep it bright in

the photo. Do the opposite

when metering a dark object

• take light away, essentially,
  to keep it dark. If you don’t,
  then the camera will assume
  that the bright object or the
  dark object should appear as
  a mid-tone in the image...

Correcting your exposures

Why your camera meter can get things wrong – and steps you can take to deal with it

T

JUST A REFLECTOR

How your camera

meters the light

The metering sensor sits near the

viewfinder and measures the

amount of light reflected up to the

focusing screen by the camera’s

internal mirror. The sensor is

configured to 18% reflectance – or

the amount of light reflected by an

object that has a mid-tone value

(such as grass or pavement, for

example). This doesn’t always work

out in the real world, which is why

some photographers take a meter

reading from a grey card and then

set the exposure manually to

ensure that they get consistent

results in shots.

Dark subjects reflect

less light; the camera

thinks the subject is

being underexposed

Mid-tone subjects should

cause no problem

Light tones

reflect lots of

light; the camera

thinks the

subject is being

overexposed

Incident light falling

on the scene

Dark^ Mid-tone^ Bright^