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)
Film sensitivity, (film speed)
Aperture
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
Fast shutter speed is needed for action
photography
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
The aperture affects the depth of focus
Large apertures, (f2, f2.8) have shallow
depth of focus
Small apertures, (f16/f22), have huge depth
of focus
Effects of Aperture
Camera focussed at 3m
2.8m -3.5m
2.0m – 30m
1.5m – ∞
Automatic Cameras
Most cameras have three main automatic modes
Full automatic, (great for snapshots)
Aperture priority, (camera sets shutter speed)
– Typically for portraits
Shutter priority, (camera sets aperture)
– Typically for sports
The choice depends upon the desired effect
Automatic Cameras
Modern automatics also have ‘programs’
These use either shutter or aperture priority
as per programming.
Ie ‘sports’ means shutter speed priority
Automatic Exposure
Cameras measure the correct exposure in different
ways, depending on where they measure light:
Spot - a small area in the centre
Centre weighted - a larger central area
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
Light subject against dark background
You need to underexpose
Weddings. Incredibly difficult to photograph.
Black suit stands next to white dress
Dark subject against light background, (Sky!)
You need to overexpose or use flash
Exposure Problems
Low light is big problem
Large aperture = small depth of focus
Slow shutter = camera shake
Need tripod or external light like a flash
Exposure Solutions
Over-expose in certain circumstances
Under-expose in certain circumstances
Use external lighting, flash, or reflectors
Electronic Flash
All flash have a ‘guide number’
This measures power or maximum light
output
– Small guide number = weak flash
– Big guide number = powerful flash
Film Speed
The third aspect of exposure
Different films have different sensitivities
Rated as ISO or ASA
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
Slow film has small grain and better
resolution
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
Automatic Focusing
By scale
Central spot
Through the lens
Average
– Split image
Focus
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
Average focussing presents problems if you
want a specific subject in focus, ie a flower
Composition
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
Avoid cuts at ankles, knees, waist shoulders
Always try to keep the complete body in the
picture
Positioning
Position the main image off centre
Use the ‘rule of two thirds’
Position the main subject:
2/3 across to the right
2/3 from bottom or top
Texture
Look for unusual textures
Walls, trees, rocks, and all natural products
have ‘texture’
Use unusual shapes and angles
Be creative
Shooting Position
To enhance stature look up at subject
To diminish stature look down on subject
Never look down on children, shoot at their
eye level
Framing
Add a frame for effect
Add a tree to the edge of a picture
Use an upright or post
Use overhanging branches
Photograph through openings
Be creative
Background
Watch for inadvertent background
Avoid un-necessary and distracting clutter
Avoid growths from heads
Avoid wires and cables
Fore/middle/back ground
Give pictures depth
Single distance objects make flat pictures
Put a plant at the front of a scenic shot
Think Fore-Mid-Aft
The Lens
A standard lens is like an eye
A telephoto lens makes far objects close
A wide angle lens sees wider than the eye
A macro lens is used for close ups
Focal Length
Measures angle and light gathering power of a
lens
20-35 mm = wide angle
50 mm = normal
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
For same lighting
Wide angle means fast shutter speed and
small aperture
Telephoto means slow shutter speed and big
aperture
Focal Length and Exposure
A telephoto lens induces camera shake
At 200 mm focal length minimum shutter
speed is 1/125
Telephotos do not have big apertures
Telephotos in low light are a problem
Perspective
Long focal length, (telephoto), reduces
perspective, ie objects are ‘stacked’
Short focal length, (wide angle) enhances
perspective, ie objects are ‘spread’
Colour Temperature
Film is ‘balanced’ to show true colours
Different light sources give out different
colours of light
You need to choose the correct film for
correct the light source
Colour Temperature
Tungsten light bulbs are ‘cold’ and give
daylight film a yellow cast
Fluorescent tubes give a cold grey cast
Flash is designed to match sunlight for
colour temperature
Sony PSC8 and PSC10
Sony Cybershot cameras have the ability to
take excellent pictures
But they need to be used correctly
To take good pictures you cannot simply
point and shoot
Taking a Picture
When the shutter is depressed the camera:
Sets the focus
Sets the exposure
Sets the white balance
Focus
The camera can be used in either manual or
automatic mode
Manual is set using a distance scale
Automatic has two modes
Auto Focus
There are two modes:
Multipoint AF
Centre AF
Focus Lock
To focus on an off centre subject
Centre subject and half depress the shutter
Recompose picture
Fully depress the shutter
Monitoring Focus
The camera has 3 switchable modes:
Single. As shutter is depressed
Monitoring. Before the shutter is depressed
Continuous. Before and during exposure
Macro
The minimum focus distance is 50 cm
For close ups use macro
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
Off centre subject
Low light
Moving subject
Reflective subject
Low contrast subject
Backlit subject
Exposure Metering
The camera has two metering modes:
Multi Pattern. Average metering across the
image
Spot.
Centre subject on cross hair.
Exposure Programs
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
Bright subject against dark background
Underexpose the image by decreasing EV
Flash Photography
There are 4 flash modes and 3 levels
Auto, (no symbol)
Forced flash
Slow Synchro
No flash
Film Speed
Set automatically by camera
Can also be manually set at ISO
100 200 400
White Balance
Can be set manually
Flash
Incandescent
Florescent
Cloudy
Daylight
Auto (no symbol)