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APERTURE
Aperture
Defined
According to www.merriam-webster.com the
definition of aperture is as follows:
ap·er·ture (āp’ər-chər) – noun – a : the
opening in a photographic lens that admits the light b : the diameter of the
stop in an optical system that determines the diameter of the bundle of rays
traversing the instrument.
How
it works
The aperture is like the pupil of an eye. The aperture blades
make the opening bigger or smaller, just like the iris makes the pupil dilate
larger and smaller to allow in more or less light. In a dark setting, the iris
opens up to let more light in and in a bright setting, the iris closes down
since not as much light is needed to see any surroundings.
A camera has a lens with a diaphragm that
opens and closes based on the lighting, automatically or manually, in order to
regulate the amount of light that reached the film or sensor.
Nevertheless, in a camera, there are other
factors that work with the aperture to control the exposure such as shutter
speed and ISO, but the basics of aperture by itself are much like the eye.
How
it is controlled
The aperture settings of a film camera
lens, whether a 35mm, medium format, or large format camera, is set by what are
known as f-stops. All lenses are marked with specified f-numbers, which are
numbers marking the ratio of focal length to the diameter of the hole. The
lower the f-stop number the larger the aperture hole becomes, allowing more
light in to expose the film. Conversely, the larger f-stops numbers equate to a
narrower hole.
Large f-stop = Small opening
Small
f-stop = Large opening
Aperture
and Depth of Field.
Aperture has a big impact upon depth of field.
Depth of Field is that amount of your shot that will
be in focus. Large depth of field means that most of your image will be in
focus whether it’s close to your camera or far away.Small (or shallow) depth of
field means that only part of the image will be in focus and the rest will be
fuzzy.
Depth of field is determined by the aperture and the
length of the lens. The larger the aperture, the more light enters the lens,
and the smaller the depth of field. Similarly, when using a long lens the depth
of field is smaller.
SHUTTER SPEED
Definition of Shutter Speed
According to http://www.digitalrebellion.com/glossary.htm#S , Shutter speed
The amount of time it
takes for the camera shutter to open and close. Faster speeds produce
crisp motion and slower speeds produce motion-blur.
How it works
At the back of the camera, there’s a sensor that records light. This
sensor is jam-packed with light-sensitive gnomes who do nothing but wait
for light to hit them and then record whatever light they see. Most of
the time these gnomes are very bored, because there’s a curtain in
front of them that blocks out all the light. That curtain is called the
shutter .If the shutter is open for a long time, a lot of light hits the sensor
gnomes. If it’s only open briefly, the gnomes get correspondingly less
light. The amount of time the shutter is open is called, shutter speed.
Shutter speed is expressed in fractions of a second, and is most
commonly in the range of about 1/30 sec to 1/500 sec, though it can
range from many seconds up to the maximum speed of your camera–
frequently 1/2000 or 1/4000 of a second.
Shutter speed can be used to display motion in photographs. If you use a really fast shutter speed, you freeze whatever action is happening. Using a slow shutter speed will let you capture motion blur.
Shutter Speed and Aperture
As mentioned above, shutter speeds and apertures each have a standard series of settings called "stops".
- With shutter speeds, each stop is a second or more, or a fraction of second indicating how long the shutter is open.
- With apertures they are f/stops indicating the size of the opening through which light enters.
What is the difference?
Smaller aperture and slower shutter speed gives higher depth of field
but there is a risk of blurred moving objects on the picture.
A bigger aperture and higher shutter speed lead to lower depth of field but there is no risk of blurred moving objects
