2. Level 1 – Photography Basics
2
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3. Photography Basics
Contents
What is Photography
What is a camera
Camera types
How photography works
Shutter speed
Aperture
ISO
Using the camera
Exposure
3
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7. What is a
camera?
Photography Basics
•
•
Controls to alter the amount of light
recorded
•
7
A light-tight box to hold film or
digital sensor
Lens to focus light
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9. Photography Basics
Camera types
•
Compact or SLR
•
Aimed at different markets
•
Compact
– Low-end consumer
– Point and shoot
•
SLR
– Users with interest in photography
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10. Compact or
SLR?
Photography Basics
Compact
SLR
•
•
Larger
•
Lower cost
•
More expensive
•
Small sensor
•
Larger sensor
•
Standard performance
•
Higher performance
•
More versatile
•
Through-the-lens viewing
•
Interchangeable lenses
•
More user control
•
10
Small
Extensive accessories
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14. Photography Basics Shutter speed
•
•
Most EOS cameras have a range from
30s to 1/8000s
•
1/2000s – 1/8000s = very fast shutter
speeds
•
1/250s – 1/1000s = fast shutter speeds
•
1/8s – 1/125s = slow shutter speeds
•
14
Measured in stops
30s –1/4s = very slow shutter speeds
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20. Photography Basics
Camera shake
•
•
General hand holding rule: use 1 divided
by the focal length of the lens, i.e.,
1/focal length
•
E.g. with a 200mm lens, use 1/250s
or faster when hand holding
•
20
Slow shutter speeds can cause camera
shake
If shutter speed is less than hand-holding
speed, use a tripod
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21. Image
Stabilizer
Photography Basics
•
Some lenses feature Image Stabilizer technology
•
Helps avoid camera shake with slower shutter speeds
•
Allows you to hand-hold a lens with a shutter speed 3-5
stops slower than the rule on the previous slide
•
E.g. 200mm lens should be hand-held at 1/250s but
could be hand-held at 1/30s to 1/8s depending on the
IS system
Hand holding a 200mm lens
IS
1/2
1/4
1/8
1/15
1/30
Lower speeds possible with IS
on
21
1/60
1/125
1/250
1/500
1/1000
1/2000
1/4000
1/8000
Without IS
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23. Image
Stabilizer
function
Photography Basics
•
A special group of lens
elements are moved to
counteract camera
shake
•
Two modes on some
lenses
– Mode 1 for everyday
use
– Mode 2 for panning
with a subject
•
23
EF-S 55-250mm f/4-5.6
IS lens automatically
detects panning
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25. Photography Basics
Aperture
•
•
Aperture range determined by lens
•
Controls amount of light let in
•
Low number e.g. f/2 lets in more light
•
25
Measured in stops called f-stops
High number e.g. f/22 lets in less light
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26. Aperture
Photography Basics
Quick Control Dial
•
EOS 40D, EOS 5D, EOS-1 series
– Use Quick Control Dial to adjust
aperture
AV Button
•
EOS 450D
– Use AV button and Main Dial to
adjust aperture
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29. ISO speeds
Photography Basics
•
ISO – the third parameter that controls the amount of light recorded
•
Measured in stops
•
Affects the sensitivity of the sensor to light
•
Range from L (ISO 50) to H (ISO 6400) depending on model
ISO Scale
50
29
100
200
400
800
1600
3200
6400
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30. Photography Basics
ISO range
ISO 3200
1600
ISO 800
- Very low
- Low light
light
ISO 200
shooting
ISO 400
- Image
ISO 100
Image
Possibility
noise for
- Good
noise for
- Good be
of some
could
general
- Best quality
likely
image noise
lower light
marked
shooting
30
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33. Photography Basics
How to hold
the camera
•
•
Use a firm grip with the right hand
•
33
Support the weight of the camera with
the left hand under the lens
Use either left or right eye to look
through the viewfinder
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34. Photography Basics
•
Pressing the
shutter
button
2 stages
– Half pressure activates the camera,
takes an exposure reading and
activates autofocus
– Full pressure releases the shutter to
take a picture
34
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36. Exposure
Photography Basics
•
Exposure is controlled by shutter speed, aperture and ISO
•
These settings balance to give correct exposure
•
You can use a variety of combinations of these settings and still retain
the same exposure
1/1000
1/500
1/250
1/125
1/60
1/30
1/15
All of these combinations give the same exposure
f/2.8
36
f/4
f/5.6
f/8
f/11
f/16
f/22
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39. Photography Basics
What have we
covered?
What is Photography
What is a camera
Camera types
How photography works
Shutter speed
Aperture
ISO
Using the camera
Exposure
39
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Editor's Notes
These are the topics we will cover in this presentation
Capturing light on a film or digital sensor.
Many genres and styles.
Both science and art .
Can be for professional use as a job, or simply to record memories.
- A Camera is a light-tight box to hold film or digital sensor.
The Lens focuses the light rays.
Various controls to affect how much, and how the light is recorded.
Technological changes have occurred, such as digital recording replacing film, but the camera is still essentially the same as it has always been.
There 2 types of camera in the Canon range.
Compact camera like Powershot G9 or IXUS range.
SLR cameras like EOS 450D, EOS-1D Mark III.
They are aimed at different market segments – Compacts for everyone, SLRs for users more deeply interested in photography.
- Compacts are suitable for beginners and any user wanting to record memories.
- SLRs offers more versatility, higher performance and image quality. However they also requires more input and knowledge from user.
- SLRs are suitable for beginners to advanced users.
Photography means painting with light. The amount of light recorded can be controlled by three settings – shutter speed, aperture and ISO. These settings are measured in ‘stops’ or fractions of stops – full stops, half stops and third stops.
A stop is simply a relative measure of light. Each stop change doubles or halves the amount of light recorded.
If one light bulb equals one stop, two light bulbs would be two stops, 4 light bulbs would be 3 stops, and 8 light bulbs would be 4 stops etc.
Now, some photographic terms that we will use frequently:
Aperture: Most photographic lenses contain an iris diaphragm, which made up of a series of interlocking metal blades arranged to leave a hole, or aperture, at the centre. As the blades move, the size of the aperture changes.
Shutter Speed: The amount of time the light is allowed to pass through the aperture.
ISO: The sensitivity of film emulsion to light is called its 'speed' and is given an ISO (International Standards Organisation) rating, e.g. ISO 50 is a low sensitivity and ISO 1600 high sensitivity. The sensitivity rating of digital sensors follow the same scale.
The scale shows the full stop scale of shutter speeds.
Shutters are made of two curtains that move independently.
The first shutter curtain moves, then after a period of time, the second shutter moves.
They move from top to bottom exposing the sensor as they travel.
For fast shutter speeds, the first shutter will not have reached the bottom before the second shutter fires, creating a moving slit of light.
In this animation, the red curtain is the first curtain, the grey curtain is the second curtain.
Here we see examples of how the same subject (a water fountain) shot at different shutter speeds can look very different. Slow shutter speeds allow the water to blur creating an impression of movement. Fast shutter speeds ‘freeze’ the water movement.
The main command dial is located just behind the shutter button. Rotate this to change shutter speeds. The current speed will be shown on the rear LCD display or the top panel LCD display and in the viewfinder.
When you take a picture using flash, these are the steps the camera goes through to ensure a correct flash exposure.
When using flash, the flash duration is very short and the flash has to fire at the same time as the shutter is open. With fast shutter speeds the shutter opening is only a narrow slit that travels across the sensor, so a single flash burst will only illuminate that slit. The result would be that only a narrow band is exposed on the sensor or film. The maximum shutter speed at which the flash can illuminate the whole scene because both shutter curtains are fully open is called the synchronisation or sync speed.
With settings faster than the maximum sync speed, the flash – if it is able to – must fire repeatedly during the exposure to expose each part of the image. However this rapid flashing or ‘strobing’ does reduce flash power and therefore the distance at which the flash can be effective.
Slow shutter speeds can cause the camera to move during the exposure creating images which are not sharp. This is called camera shake.
When hand-holding the camera try to use a shutter speed at least as fast as the focal length of the lens.
e.g.
200mm lens – use a shutter speed of 1/200s or faster (in practice the nearest marked speed is 1/250s)
50mm lens – shutter speed of 1/50s or faster (the nearest marked speed is 1/60s)
Certain lenses feature an Image Stabilizer function. This helps compensate for slow shutter speeds and allows you to continue hand –holding when using slower shutter speeds.
It cannot counteract subject movement.
Depending on the lens, Image Stabilization provides 3-5 stops of effective shutter speed increase (i.e. you can hand hold the camera and lens at shutter speeds 3-5 stops slower than you could with Image Stabilization switched off )
Left – IS turned OFF – note the image blur caused by camera shake.
Right – IS turned ON – camera shake is reduced and the image becomes much sharper.
The IS feature is only found on some lenses.
Mode 2 function for panning is not found on all IS lenses.
IS functions by detecting the movement of the camera and moving a specific lens group to bend the light rays back to parallel.
The Aperture is the size of the hole in the lens. It regulates the amount of light coming into the camera. A bigger hole allows more light to pass, and a smaller hole allows less light.
The aperture is adjusted in slightly different ways according to the camera model.
Taken with an EF50mm f/1.2L USM lens.
Shows apertures changing from f/1.2 to f/16 in whole stop increments.
ISO stands for International Standards Organisation. The ISO scale is a rating of the sensitivity of film to light, originally for film use. The term and ratings have been carried over to digital to ensure parity and easy understanding by users.
Each increase on the scale effectively makes the sensor twice as sensitive to light.
In fact, changing the ISO does not affect the sensor at all, it simply changes the amplification of the signal received from the sensor.
Changing the ISO rating does affect the image in more ways than just modifying the exposure.
As with film, higher ISO ratings produce more grain, or digital noise. This appears as speckles in the image.
High ISO ratings also create larger file sizes so fewer images can fit on a card.
The following sequence shows ISO 100 to ISO 3200 with an EOS 40D.
Setting the ISO is quick and easy. The ISO speed is displayed in the LCD panel on the top (for the EOS 40D, EOS 5D and EOS-1 series cameras) and on the rear LCD screen for the EOS 450D.
Some cameras e.g. EOS 450D have a second way to change the ISO, by pressing the ISO button and using the cross keys on the rear of the camera.
Holding the camera correctly can have a beneficial effect on the sharpness of the photographs. It also makes the camera more comfortable to use especially when using the camera for long periods.
The shutter button has two stages – a first half pressure activates the camera, then pressing it fully down releases the shutter to take a picture.
As we have learned the exposure can be adjusted by changing the shutter speed, aperture, or ISO or by a combination of all three settings.
Certain combinations of shutter speed and aperture give the same exposure – i.e. The camera might indicate an exposure of 1/125s at f/8 to give correct exposure. For this same light condition you could also use 1/1000s at f/2.8, or 1/15s at f/22 and still get the same exposure – although the resulting image might look somewhat different in terms of subject movement and depth of field.
The green scale shows various possible shutter speed and aperture combinations that would give the same exposure for this particular light level.
If we filled a glass with water using a pipe, it could be filled quickly – using a large diameter pipe, or if using a narrow pipe - slow.
In this example the pipe diameter can be considered similar to the aperture of a lens, and the time it takes to fill the glass is similar to the shutter speed.
The three images that follow show 1) the correct exposure, 2) too little exposure (underexposure) and 3) too much exposure (overexposure).
Although the camera will get the exposure right most of the time, it simply reads REFLECTED light.
This works well, but if the subject reflects a lot of light, or not very much light – i.e. is very light or dark – the exposure reading made by the camera could be incorrect. This particular subject will be covered in more detail in Level 2.
