Fiddling With Your Fiddling With Your Camera

or How I learned to stop worrying and just press the darn release ...

Technical Parameters

Focal length time Sensitivity Technical Parameters

Focal length (determines field of view) Aperture (determines ) Exposure time (affects motion in your image) Sensitivity (affects film/sensor response level) Which parameters matter most? Which parameters matter most?

Focal length: 50 mm Exposure time: 1 s Aperture: f/8 Sensitivity: ISO 200 Which parameters matter most? Which parameters matter most?

Focal length: 100 mm Exposure time: 1/125 s Aperture: f/16 Sensitivity: ISO 200 Focal Length Focal Length

Two types of lenses:

 prime (one focal length)  zoom (many focal lengths) Focal Length

Directly determines field of view Indirectly determines perspective

50 mm 135 mm

Your position, not the lens, determines perspective! Wide Angle Lenses

Roughly 35 mm and shorter Short focal length large field of view Wide Angle Lenses Wide Angle Lenses

Focal length: 18 mm Wide Angle Lenses

Challenge: organize the chaos!

 How does one image element relate to another?  Hard to use effectively Wide Angle Lenses

Creative possibilities:

 Get close! (exaggerates perspective)  Drop your viewpoint

 Find a strong foreground element

Focal length: 17 mm

Focal length: 24 mm

Focal length: 17 mm Telephoto Lenses

Roughly 85 mm and longer Long focal length narrow field of view

What are telephoto lenses good for?

Focal length: 420 mm Pick Out Details

Narrow field of view pick out distant details

Focal length: 135 mm

Focal length: 100 mm Compressed Perspective

Telephoto lenses don’t compress However, distant objects appear closer together Compressed Perspective Compressed Perspective

Focal length: 200 mm

Focal length: 77 mm

Focal length: 135 mm Control of Backgrounds

Narrow field of view:

 Find a pleasing background for your subject  Avoid distractions

Focal length: 420 mm

Focal length: 260 mm

Focal length: 160 mm

Focal length: 200 mm Avoid Distractions

Two examples:

 Avoid undesirable patches of sky  Keep verticals straight

Focal length: 70 mm

Focal length: 110 mm Aperture Aperture

Refers to size of opening of the lens Expressed relative to the focal length of the lens

f-number = focal length / lens diameter Aperture

Denoted using f-numbers (f-stops): f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22

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Why the strange number sequence? Why The Strange Numbers?

Denoted using f-numbers (f-stops): f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22

Each number is bigger than previous one by sqrt(2) Example: let’s change aperture from f/2.8 to f/4

 lens diameter shrinks by sqrt(2)

 lens area decreases by factor of 2

Therefore, f/4 admits half the light of f/2.8 F-Stops

f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22

F-stop: refers to the doubling or halving of light

Common language:

 stopping down (higher f-numbers)

 opening up (smaller f-numbers)

 wide open (maximum aperture)

Example: stop down two f-stops from f/4 to f/8 Identifying Lenses

Lenses are identified by:

 focal length (or range of focal lengths)

 maximum aperture

Examples:

 135 f/2

 17-40 f/4

 17-85 f/4-5.6 How To Change Aperture?

Traditional

 mechanical aperture ring

 set aperture by touching lens

Current:

 electronically-controlled

 set aperture on camera Electronic Diaphragm

Common usage:

 focus and compose at maximum aperture

 camera tells lens to stop down at shutter release

 can also stop down using depth of field preview

Some nice benefits:

 bright viewfinder during composition

 helps autofocus Depth Of Field

Main creative application of aperture Bigger aperture less depth of field

50 mm f/1.4 135 mm f/2 Why Shallow Depth of Field?

Better subject-background separation Make the subject stand out

135 mm f/2

420 mm f/4

200 mm f/4 Why Shallow Depth of Field?

Incorporate out-of-focus areas into the image Really big lead to a dreamy background

85 mm f/1.2

85 mm f/1.2

300 mm f/2.8 Another Way To Lose Depth Of Field

Closer focusing less depth of field

200 mm (+diopter) f/13 Stopping Down

How far to stop down? Just enough to get the depth of field you need!

100 mm f/16

135 mm (+diopter) f/22

135 mm (+diopter) f/22 Exploiting Diffraction

Light bends as it passes through small slits or holes

24 mm f/22

17 mm f/22 Aperture Summary

Expressed in f-stops (e.g. f/2.8, f/4, f/5.6, ...) F-stop: a doubling or halving of light

Stop down smaller aperture, more depth of field Open up bigger aperture, less depth of field

Controlled electronically in modern lenses Lenses denoted by focal length and maximum aperture Exposure Time Exposure Time

Controls amount of time the shutter is open More time more light Exposure Time

Measured in seconds or fractions of a second Convenient to think in stops, too:

 1/15 is one stop slower (longer) than 1/30

 1/100 is one stop faster (shorter) than 1/50

1/2000 1/20 1/2000 1/20 same exposure f/4 f/32 Freeze Or Blur?

More time more blur Affects the sense of motion in the image

300 mm f/3.5 1/640

300 mm f/3.2 1/400

145 mm f/5.6 1/2500

50 mm f/8 1/2

115 mm f/22 1 s

50 mm f/8 1/2

17 mm f/8 1/250

100 mm f/8 1/50

35 mm f/4 1 s

24 mm f/22 30 s Sensitivity Sensitivity

Determines response of film/sensor to light More sensitivity more response Measured in ISO values:

 ISO 100, 200, 400, 800, 1600, 3200, ...

 ISO 200 provides 2x response of ISO 100 Sensitivity Tradeoff

Higher ISO value:

 shorter exposure time (for same exposure level)

 more noise

Current digital SLRs have excellent noise control

 use the necessary ISO to get the shot you want! ideal: 50 mm f/8 ISO 100 1/5 s 50 mm f/5.6 1/80 ISO 800

300 mm f/3.5 1/640 ISO 800 Which Parameter Values?

1. Find correct exposure

2. Figure out which parameters matter the most 3. This determines the rest of the parameters

100 mm f/16 1/125 ISO 200

85 mm f/1.2 1/100 ISO 1600

280 mm f/5 1/1000 ISO 400

130 mm f/22 1/8

50 mm f/16 1/2

75 mm f/5.6 1/1250

1/200 s 1/4 s

300 mm f/2.8