Shutter Speed and Aperture
Controlling Exposure
http://www.photonhead.com/beginners/shutterandaperture.php
What do shutter speeds do ?
http://www.mir.com.my/rb/photography/fototech/apershutter/shutter.htm
In principle, shutter speeds, like aperture value contributing as the next half of the main components for any exposure process - the interval at which the shutter opens to allow a specific amount of light (also depends on the opening of the lens diaphragm) to pass through and expose the film inside..
Different selection of shutter speeds will yield different kind of visual effect on a final photograph. Generally, a fast shutter speed can freeze action while slow speed can blur your image.
If you understand the nature of how various shutter speed(s) will affect an exposure, you may put them to creative use to enhance the effect - like other than freezing a fast action scene, a slow shutter speed can also put to good use in portraying movement. You can try on to "PAN" a moving subject by following its direction or simply generates a sense flow of movement.
For the creative minded photographer, slower shutter speed sometimes may create a more powerful visual impact than images taken with action-freeze high shutter speed(s), say, a free flowing river, traffic, a flock of birds taking off or even speed-demons on a race track.. etc..
In order for an image to be captured on film, it must be exposed to light.
The camera has two settings that control light, and they work very similar
to the human eye.
The Shutter:
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The shutter blocks all light from exposing the film UNTIL you press the button. Then it quickly opens and closes, giving the film a brief flash of light. You can control the length of time the shutter remains open by setting the SHUTTER SPEED.
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The Aperture:
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Before light reaches film, it must pass through an opening called an "Aperture". The aperture is like a pupil. You can control the aperture by setting the "Aperture Opening", also known as an F-Stop. Smaller F-stops numbers = larger openings larger openings = more light |
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Shutter Speed:
Determines HOW LONG the shutter stays open.
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The longer exposures ( like 1 second ) give much more light to the film than a 1/1000 of a second exposure. So even though the number may look bigger, don't be deceived!
« Every step in this table |
Aperture Settings (F-Stops):
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Like the pupil in a human eye, the aperture on a camera controls light. It does so by closing up to restrict light, and opening up to let it through. Examples:
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Balancing Shutter and Aperture:
Exposure is about different combinations of shutter and f-stop settings.
These combinations can drastically affect the finished picture. For example,
the following three pictures have been given an equal amount of light, but
the f-stop and shutter combinations make each one unique.
Why is the background all blurred in the right picture, and sharpest in the left ? Because if the exposure is made with a wide aperture ( like f2.8 ), then objects farther away from the subject are thrown farther out of focus. This effect is referred to as "depth of field"
So.. if the aperture is small (like f22) then objects in the background (and foreground ) will appear sharper. However, since more light was required to make the exposure on the left ( 1/4 Second ) the subjects became blurred from MOTION. At 1/250th of a second, the shutter is fast enough to freeze motion.
Take a stop, Give a stop..
Since f-stop and shutter are both measured in stops, keeping balance is
easy. If you take away 2 stops from the aperture, you can give 2 stops back
with the shutter and end up with the same exposure level.
Picture courtesy of Vincent Thian, AP; Nick Kalatha, US and Swan pictures by David Hofmann, Germany
Selection of FAST or SLOW shutter speeds may yield different visual effect in a photograph
basically, it is FREEZE or MOTION CREATING. The FREEZE can also be use to minimize hand shake, the BLUR may be use for artistic effect; in some situations, you may use slow shutter speed because the permitting ASA/ISO range of the film in use or aperture on the lens are at their limit. The swan pictures by David was a very good example as side by side comparison between use of HIGH shutter speed and LOW speed is used.