CLASS NOTES
APERTURE
What is aperture?
Shutter speed is a fairly simple concept to understand because we
all understand the notion of time (and fractions of it).
Aperture, on the other hand, is a little different. Aperture
(meaning ‘opening’) is an iris in the lens —
a small set of interlocking blades that control
how much light enters the camera. A bigger hole (or ‘larger
aperture’) will allow more light, meaning a brighter image; a smaller hole
(or ‘narrow aperture’) allows less light, meaning a darker image.
How is aperture measured?
Aperture is measured in ‘f-stops’. An
f-stop (e.g. f/8) specifies the size of the hole, and is a number
that refers to the ratio of the size of the aperture to the focal length of the
lens. A high f-stop number (e.g f/22)
means that the aperture hole is small;
a low f-stop number (e.g f/4)
means that the aperture is large, or wide open.
TIP: Moving from one f-stop to the next
either doubles or halves the amount of light allowed
in to the camera.
What does the aperture do?
Much like shutter speed, aperture plays both a technical and
creative role. First, the aperture (like shutter speed) controls the
amount of light let in to the camera’s sensor, thereby affecting the
exposure. Second, the aperture affects how much of the image is in focus,
something referred to as depth of field.
What is depth of field?
Depth of field (DOF)
is the area of your image that is in focus.
A large depth of field — signified by a
larger f-stop number (e.g. f/16) — means that
more of your image will be in focus whether it’s close to your camera or far away.
A small, or shallow, depth of field —
signified by a smaller f-stop number (e.g. f/4) —
means that only
part of the image will be in focus and the rest will be blurred.
SHUTTER SPEED
What is shutter speed?
Shutter speed refers to the length of time a camera’s shutter is open for, and subsequently how long the digital sensor (or film) is exposed to light in
order to capture the scene.
How is shutter speed measured?
Shutter speed is measured in seconds or, in most cases, fractions of seconds (e.g.
1″, 1/2, 1/15, 1/125, 1/1000). The larger the denominator, the faster the speed (i.e. 1/500 is faster than 1/30
which, in turn, is faster than 1/4).
How does shutter speed affect my images?
The shutter speed plays both a technical and creative role. First,
changing the shutter speed alters the amount of light let in to the camera,
thereby affecting the overall exposure. Second, adjusting the shutter speed
allows the photographer to either freeze or blur motion.
Here are some guidelines for selecting shutter
speed:
- To freeze motion, choose a faster shutter speed.
- To blur motion, choose a slower shutter speed.
- EXPOSURE
- The exposure triangle
- A photograph’s exposure, as captured by your camera, determines how light or dark an image will appear.
- The three fundamental elements of exposure are:
Together,
these make up what is known as the exposure triangle and
form the foundation of successful photography.
Capturing a
correct exposure is a balancing act between shutter speed, aperture and
ISO.
You can use both shutter speed and aperture to alter the amount of light
that strikes the sensor, however, as one increases, the other has to decrease
to maintain the same exposure level, and vice versa.
For example, as your
aperture opens, and lets in more light, your shutter speed will have
to increase (i.e. a faster shutter speed) in order to compensate — if
you want to maintain the same exposure level.
If your aperture narrows,
and lets in less light, your shutter speed will need to decrease
(i.e. slower shutter speed) to balance that out.
NOTES
- Aperture affects depth of field, shutter speed affects motion blur and ISO affects image noise
- Although the aperture is the main factor affecting depth of field, there are a number of other considerations, including:
- Focal length
- Sensor size
- The distance between you (i.e. the photographer) and your subject. Get nice and close to your subject to achieve shallow focus.
- The distance between your subject and the background – The further away the background is from your subject, the more blurred the background is going to be.
Wide-angle
Aperture 22 – Result was a very blurry photo. Maybe if I used a tripod, it would eliminate the camera shake.