Digital SLR Photography - UK (2019-12)

MANAGING DEPTH-OF-FIELD IS NOT ONLY IMPORTANT FOR SHARPNESS BUT IS

ESSENTIAL TO HELP YOU DEVELOP YOUR SKILLS AS A CREATIVE PHOTOGRAPHER

APERTURES & DEPTH-OF-FIELD

D

EPTH-OF-FIELD REFERS to the extent

of sharpness within an image, which

extends in front and behind your point

of focus. Depth-of-field can be mere

millimetres or extend from the nearest to the

furthest areas of the scene. You can control

depth-of-field through a number of factors,

but none is as easy or as effective as simply

adjusting your aperture setting.

The relationship between apertures and

depth-of-field is intricate; you cannot adjust

your aperture without affecting depth-of-

field, but you can adjust depth-of-field

without changing your aperture. It’s a close

and somewhat complex relationship to

understand but, once you do, you’ll be able

to take control and manipulate depth-of-

field as you see fit whether you’re shooting

landscapes, close-ups or portraits, as each

calls for a different approach.

The direct link between aperture choice

and depth-of-field is simple: the wider the

aperture, the shallower the depth-of-field;

the smaller the aperture, the greater the

depth-of-field – or, in other words, the

deeper your zone of sharpness. If you want a

small area to apear sharp, for instance a face

in a portrait, you’ll most likely need to select

a wide aperture such as f/2.8 to achieve that

soft fall-off in focus past the ears. If you want

your scene sharp from front to back, a small

aperture such as f/11 or f/16 is the way to go.

There are ways to achieve more or less

depth-of-field, however, without adjusting

your aperture: your lens type and camera-

to-subject distance, for instance. Knowing

how these can manipulate depth-of-field

won’t mean you’re limited to your aperture

setting, which pays dividends if you need to

giving the illusion of a shallower depth-of-

field compared to a wide-angle lens, which

delivers an apparent greater depth-of-field

at the same aperture because of its wider

field-of-view. It’s why you can photograph a

portrait using a 35mm lens at f/1.4 and still

get sufficient depth-of-field for a sharp

image, whereas with a 85mm from the same

distance you’ll be working with a much

thinner plane of focus. This brings us on to

sensor size, should this not be confusing

enough for you; when considering your

maximise available light and depth-of-field.

The distance between subject and

camera, known as shooting distance, has a

major effect on depth-of-field. No matter

what aperture you set, the closer you are to

your subject, the shallower your depth-of-

field will be. For instance, if you were to shoot

a subject a metre away at f/8 your depth-of-

field will be far less than if you were using f/8

five-metres away. Add in the fact both focal

length and lens type also affect depth-of-

field and you’ve a number of variables to

work with. The longer your focal length, for

instance, the less depth-of-field it will give

you at any given aperture. You also have to

consider the type of lens: a telephoto has

pulling power that compresses perspective

focal length do so in relation to your camera’s

sensor size, as while a 50mm lens is 50mm

on a full-frame camera, it’s 75mm (80mm

with Canon) with an APS-C sensor given the

1.5x (1.6x on Canon) crop factor. In other

words, a 50mm lens at f/2.8 used with

full-frame gives more depth-of-field than a

50mm on APS-C as the smaller sensor

increases the effective focal length. This is a

basic explanation but it’s enough to get on

with when experimenting with your own

camera and lens combinations.

Photo Masterclass

Youcanseeherehowwitheachstop,depth-of-fieldgets

largerandmoreofthebackgroundbecomesidentifiable

anddistracting.Byfarthemostappealingpictureshere

areshotwideopenat f/2andf/2.8– thebackgroundis

smoothandthesubjectsharpandbright.Asyoustop

down,eventof/4andf/5.6,whicharecommonly

consideredthe'safesettings'forbeginnersin portrait

photography,theappealbeginstowainasthe

backgroundnearestthesubjectstartstodistractthe

viewer'seye.Seehowstoppingdowntof/8-f/16resultsin

furtherdepth-of-fieldthatdrawsattentionawayfromthe

subject'sfaceandintothedistance.

DEPTH-OF-FIELD COMPARISON

50 Digital SLR Photography December 2019

This button is usually located near the lens

mount on your DSLR. When pressed, the DOF

Preview button allows you to see the final image

before you press the shutter button. It stops

down the lens to the aperture you have set so

that you can preview the depth of focus through

the viewfinder or LCD monitor. Experiment with

the feature by setting a wide aperture, then press

and hold the DOF P review button. Slowly close

down the aperture by changing f/stops, pressing

the button in-between to see the effect. You’ll

notice how the viewfinder gets darker as you

stop down. Many cameras now offer an

electronic depth-of-field preview via the LCD

monitor, that has the advantage of showing the

changes without darkening the display.

HOW TO U S E DOF PREVIEW

THE RELATIONSHIP BETWEEN

APERTURES AND DEPTH-OF-FIELD

IS INTRICATE; YOU CANNOT

ADJUST YOUR APERTURE WITHOUT

AFFECTING DEPTH-OF-FIELD

F/2 F/2.8

F/5.6 F/8 F/11