Transcript Document

Photogaphy
How to produce a photograph
And avoid a snapshot
Fundamentals of photographs

For good pictures you need:

Good exposure

Spot on focus

Careful composition

Special effects
Correct Exposure

It is important that the correct amount of
light reaches the film

Too much light = overexposed = a bright
image

Too little light = underexposed = a dark
image
Correct Exposure

Exposure depends upon 3 things

Size of hole in lens, (aperture)

Time film exposed, (shutter speed)
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Film sensitivity, (film speed)
Aperture
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Aperture is also called f stop.
 The smaller the number the bigger the hole
 Each stop is double the area of the next

f4 lets in 8x more light than f11
Shutter Speed

The shutter speed is the time the shutter is
open.

This is the time the film is exposed to the
light
Shutter Speed

Each step in shutter speed doubles or halves the
light
1000 500 250 125 60 30 15 8 4 2 1
Fast
Slow

1000 means
, 30 means
Exposure

The correct exposure is measured by an
exposure meter

Metering can be internal in the camera

Professionals use hand held meters to
measure reflected light.
Exposure


Correct exposure is balance
If your meter says f8 at 125 is the correct exposure
 Changing f8 to f5.6 doubles light input
 Changing 1/125 to 1/250 halves light input
Exposure
If this is the correct exposure
Then so are:
f5.6 at 1/250
f11 at 1/60
f22 at ?
f4 at ?
Effects of Shutter Speed

Slow shutter speed (<30) causes camera
shake
 Note flash synchronizes at 1/30
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Fast shutter speed is needed for action
photography
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Slow shutter speed is needed for low light
Correct Exposure

There are several choices for correct
exposure

The values chosen depend upon
– Physical constraints
– Desired effect
Effect of Aperture
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The aperture affects the depth of focus
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Large apertures, (f2, f2.8) have shallow
depth of focus

Small apertures, (f16/f22), have huge depth
of focus
Effects of Aperture
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Camera focussed at 3m
2.8m -3.5m
2.0m – 30m
1.5m – ∞
Automatic Cameras
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Most cameras have three main automatic modes
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Full automatic, (great for snapshots)
 Aperture priority, (camera sets shutter speed)
– Typically for portraits
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Shutter priority, (camera sets aperture)
– Typically for sports
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The choice depends upon the desired effect
Automatic Cameras
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Modern automatics also have ‘programs’
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These use either shutter or aperture priority
as per programming.
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Ie ‘sports’ means shutter speed priority
Automatic Exposure
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Cameras measure the correct exposure in different
ways, depending on where they measure light:
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Spot - a small area in the centre
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Centre weighted - a larger central area
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Average - over the whole image
Automatic Exposure

No one exposure method is good for all
pictures

You may need to change metering to suit
conditions

Professionals use hand held meters.
Exposure problems
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Light subject against dark background
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You need to underexpose
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Weddings. Incredibly difficult to photograph.
Black suit stands next to white dress
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Dark subject against light background, (Sky!)
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You need to overexpose or use flash
Exposure Problems
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Low light is big problem
 Large aperture = small depth of focus
 Slow shutter = camera shake
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Need tripod or external light like a flash
Exposure Solutions
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Over-expose in certain circumstances
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Under-expose in certain circumstances
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Use external lighting, flash, or reflectors
Electronic Flash
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All flash have a ‘guide number’
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This measures power or maximum light
output
– Small guide number = weak flash
– Big guide number = powerful flash
Film Speed
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The third aspect of exposure
 Different films have different sensitivities
 Rated as ISO or ASA
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800 400 200
Fast
Large grain
100
50
25
Slow
Small grain
Setting Film Speed


It is important to set the camera to the
correct film speed for a correct exposure
It is possible to over or under expose on the
film speed dial.
 Moving dial from 100-50 overexposes by 1
stop
Film Speed
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Slow film has small grain and better
resolution
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Fast film has large grain and poor resolution

Generally use ASA 100- ASA 200
 Professionals use ASA 50
Focus
To give pin sharp pictures you must focus
Manual Focusing
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Automatic Focusing
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By scale
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Central spot
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Through the lens
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Average
– Split image
Focus
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Central focussing presents problems when
the subject is not centred

IR or automatic focussing is usually central.
Use focus lock for an off centre image
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Average focussing presents problems if you
want a specific subject in focus, ie a flower
Composition
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Once the exposure is correct and the focus
spot on you need to think of composition
Photography is an art
 Be creative
 (But follow certain rules)
Un-natural Cuts
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Avoid cuts at ankles, knees, waist shoulders
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Always try to keep the complete body in the
picture
Positioning
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Position the main image off centre
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Use the ‘rule of two thirds’
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Position the main subject:
 2/3 across to the right
 2/3 from bottom or top
Texture
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Look for unusual textures
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Walls, trees, rocks, and all natural products
have ‘texture’
 Use unusual shapes and angles
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Be creative
Shooting Position
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To enhance stature look up at subject
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To diminish stature look down on subject
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Never look down on children, shoot at their
eye level
Framing
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Add a frame for effect
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Add a tree to the edge of a picture
 Use an upright or post
 Use overhanging branches
 Photograph through openings
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Be creative
Background
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Watch for inadvertent background
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Avoid un-necessary and distracting clutter
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Avoid growths from heads
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Avoid wires and cables
Fore/middle/back ground
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Give pictures depth
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Single distance objects make flat pictures
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Put a plant at the front of a scenic shot
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Think Fore-Mid-Aft
The Lens
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A standard lens is like an eye
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A telephoto lens makes far objects close
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A wide angle lens sees wider than the eye
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A macro lens is used for close ups
Focal Length
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Measures angle and light gathering power of a
lens
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20-35 mm = wide angle
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50 mm = normal
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70-300 mm = telephoto
Focal Length
Wide angle = wide view
= large light gathering area
Telephoto = narrow view
= small light gathering area
Focal Length and Exposure
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For same lighting
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Wide angle means fast shutter speed and
small aperture
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Telephoto means slow shutter speed and big
aperture
Focal Length and Exposure
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A telephoto lens induces camera shake
 At 200 mm focal length minimum shutter
speed is 1/125
 Telephotos do not have big apertures
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Telephotos in low light are a problem
Perspective
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Long focal length, (telephoto), reduces
perspective, ie objects are ‘stacked’
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Short focal length, (wide angle) enhances
perspective, ie objects are ‘spread’
Colour Temperature
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Film is ‘balanced’ to show true colours
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Different light sources give out different
colours of light
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You need to choose the correct film for
correct the light source
Colour Temperature
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Tungsten light bulbs are ‘cold’ and give
daylight film a yellow cast
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Fluorescent tubes give a cold grey cast
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Flash is designed to match sunlight for
colour temperature
Sony PSC8 and PSC10
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Sony Cybershot cameras have the ability to
take excellent pictures
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But they need to be used correctly
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To take good pictures you cannot simply
point and shoot
Taking a Picture
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When the shutter is depressed the camera:
Sets the focus
 Sets the exposure
 Sets the white balance
Focus
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The camera can be used in either manual or
automatic mode
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Manual is set using a distance scale
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Automatic has two modes
Auto Focus
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There are two modes:
Multipoint AF
Centre AF
Focus Lock
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To focus on an off centre subject
Centre subject and half depress the shutter
 Recompose picture
 Fully depress the shutter
Monitoring Focus
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The camera has 3 switchable modes:
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Single. As shutter is depressed
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Monitoring. Before the shutter is depressed
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Continuous. Before and during exposure
Macro
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The minimum focus distance is 50 cm
 For close ups use macro
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If zoom on W then the minimum distance is
10 cm
 If zoom is on T then the minimum distance
is 50 cm
Focus Problems
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Off centre subject
 Low light
 Moving subject
 Reflective subject
 Low contrast subject
 Backlit subject
Exposure Metering
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The camera has two metering modes:
Multi Pattern. Average metering across the
image
 Spot.
Centre subject on cross hair.
Exposure Programs
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Fireworks, (slow shutter, focus on infinity)
 High speed shutter, (for action)
 Beach, (sets colour balance for true blues)
 Snow, (sets colour balance)
 Landscape, (focus on infinity)
 Twilight portrait, (slow shutter, forced flash
 Twilight, (slow shutter speed)
Changing Exposure

Back lit or subject against bright
background.
 Overexpose the image by increasing EV
(exposure value)
 Use forced flash
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Bright subject against dark background
 Underexpose the image by decreasing EV
Flash Photography
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
There are 4 flash modes and 3 levels
Auto, (no symbol)
 Forced flash
 Slow Synchro
 No flash
Film Speed
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Set automatically by camera
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Can also be manually set at ISO
100 200 400
White Balance
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Can be set manually
 Flash
 Incandescent
 Florescent
 Cloudy
 Daylight
 Auto (no symbol)