Fiddling With Your Camera Fiddling With Your Camera
or How I learned to stop worrying and just press the darn shutter release ...
Technical Parameters
Focal length Aperture Exposure time Sensitivity Technical Parameters
Focal length (determines field of view) Aperture (determines depth of field) 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
large small
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 diaphragm
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 apertures 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