17E
xposure is the very heartbeat of photography –
always has been, always will be. Put simply, it
is the process of light striking a photosensitive
material, like a sensor or a piece of fi lm. As you
likely know, exposure is determined by a combination of three
settings: shutter speed, aperture size and ISO speed. Shutter
speed is the duration for which the camera’s shutter remains
open, allowing light to enter and expose the sensor (or fi lm).
The aperture – or f-stop – is the size of the adjustable lens
diaphragm, which dictates the amount of light entering the
camera. The ISO speed indicates the sensor’s sensitivity to
light. In order to achieve ‘correct’ exposure, photographers
must employ the right combination of these settings. Too much
light reaching the sensor will result in overexposed shots;
not enough and the images will be underexposed.Maximum
exposure
What is perfect exposure? How useful are histograms?
When should you use spot metering, and should you still
expose to the right? Ross Hoddinott has the answers
EXPOSURE aids, like histograms and highlight alerts,
help photographers quickly identify exposure errors.
But how do you override the recommended settings
to correct problems or to expose more creatively?
If you are shooting in Manual exposure mode,
you simply select a shorter shutter length to correct
overexposure and make your images darker, or a
slower shutter speed to make your images brighter
and correct underexposure.
If you are using a semi-automatic exposure mode
like Aperture Priority, you can use the exposure
compensation button, which is indicated by a +/-icon. By depressing this button and rotating the
control dial or wheel, you can quickly apply positive
(+) compensation to make images lighter or a
negative (-) amount to make images darker. It is best
to do this using either 1/3- or 1/2-stop increments,
using your live histogram to guide you.
Exposure compensation is an important function
for creative purposes. A word of warning, though:
remember to return the level of compensation back
to 0 once you have fi nished, or you will inadvertently
apply the same level of compensation to all
subsequent shots.When to apply exposure compensation
Ross Hoddinott
Ross Hoddinott
is one of the UK’s
leading landscape
and natural history
photographers and
a regular contributor
to the photography
press. He is the
author of several books, including The
Digital Exposure Handbook. Ross lives
in North Cornwall with his young family
and is a popular and experienced tutor.
Visit http://www.rosshoddinott.co.uk.-1 EV 0 EV +1 EV
Male banded demoiselle.
In theory, silhouettes are
the result of poor exposure,
but combined with
the right subject they can
look very striking
Nikon D850, 200mm,
1/8000sec at f/5, ISO 31