Photography One

Traci Reitz, CCA

What is depth of field?

• Depth of Field is the amount of a photographwhich is in acceptably sharp focus from theforeground to the background

Why is it useful to understand depth of field?

• It allows a photographer to control the amountof the photograph which is in sharp focus toenhance the effectiveness of the image

Everything in focusEverything in focus

Main subject in focus – background blurred but

recognisable

Main subject in focus – background blurred but

recognisable

Main subject in focus – background totally

blurred

Main subject in focus – background totally

blurred

What influences depth of field?

• The focal length of your lens: wide angle lens = more depth of field telephoto = less depth of field

• The distance from the subject: further away = more depth of field closer = less depth of field

• The aperture of your lens

Aperture

• Aperture is the opening in your lens which lets in lightreflecting from your subject

• Aperture is measured in f stops. Typically lenseswill have apertures from f2 to f36

• Just to confuse, large apertures have small numbersand small apertures have big numbers!

Aperture

• Each aperture allows in half or double the amount of light as you move up or down the f stops

• Your camera may also be able to move up and down the scale in smaller steps with 2 or 3 positions between the ‘official’ f stops

• Aperture has a significant impact on depth of field: A large aperture will give a small depth of field A small aperture will give a greater depth of

field

Why does aperture affect depth of field?

• The explanation is a little bit technical:

The non-technical explanation is simpler - it just DOES!That works for me!

F 5.61/3200

small depth of field

F 5.61/3200

small depth of field

F 111/1000

medium depth of field

F 111/1000

medium depth of field

F 361/80

large depth of field

F 361/80

large depth of field

How do you work out what the DoF will be?

• There are 5 possibilities: Ignore it – don’t worry…. be happy! Use the depth of field preview if your camera has one.

This provides you with a visual check Use the depth of field scale if your camera has one

How do you work out what the DoF will be?

• There are 5 possibilities: Ignore it – don’t worry…. be happy! Use the depth of field preview if your camera has one.

This provides you with a visual check Use the depth of field scale if your camera has one Use a depth of field calculator

Get this onlineGet this online

How do you work out what the DoF will be?

• There are 5 possibilities: Ignore it – don’t worry…. be happy! Use the depth of field preview if your camera has one.

This provides you with a visual check Use the depth of field scale if your camera has one Use a depth of field calculator Make an educated guess!

Hyperfocal Distance and Focussing

• The hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp.

• When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance to infinity will be acceptably sharp.

Hyperfocal Distance and Focussing

• There are three ways to set your focus to the hyperfocal distance: Use the scale on your lens – if you have one!

Hyperfocal Distance and Focussing

• There are three ways to set your focus to the hyperfocal distance: Use the scale on your lens – if you have one! Use a chart

Get this onlineGet this online

Hyperfocal Distance and Focussing

• There are three ways to set your focus to the hyperfocal distance: Use the scale on your lens – if you have one! Use a chart Guess!

Using depth of field

• Set your camera mode to AV - Aperture Value• Choose your subject and compose your shot• Set your chosen aperture• If you have a depth of field preview, use that to check the

DoF• Check your shutter speed• If it’s fast enough – take the picture• If it’s too slow:

Use a tripod ……. OR Increase the ISO until the shutter speed is acceptable

Shutter Speed

• Shutter speed determines the amount of time the lens remains open when you press the button

• Similar to aperture, shutter speeds double or halvethe amount of time the lens is open as you clickthrough the different speeds

• A photograph’s exposure is set by a combination of shutter speed and aperture

• Shutter speed has no impact on depth of field

Finding out more

• Google ‘depth of field’• Dofmaster website

Questions?