05-08-2009 09:42 AM
The combined use of aperture, shutter speed, and sensor sensitivity (ISO) to provide the correct amount of light to the sensor in order to produce image results that most closely resemble what you see in the viewfinder when you captured the photograph.
A camera’s Aperture is an adjustable, circular opening in the lens that both control the amount of light that the sensor receives and the depth of field of the photograph. A small aperture will produce a large depth of field but allow less light to hit the sensor, whereas a large aperture will produce a shallow depth of field, but allow a lot more light to reach the sensor.
A timed device that blocks light from reaching the sensor until the shutter button is depressed. Usually this device is mechanical, but some newer digital cameras have an electronic shutter, which means the sensor is simply turned on and off.
The amount of time the shutter allows light to reach the sensor, which is usually a fraction of a second. A faster shutter speed will be better at stopping fast moving subjects, while a slower shutter speed will allow for a smaller aperture, thus producing a larger depth of field.
SensorAn electronic device composed of a light-sensitive material that first converts light to an electric signal then to digital information which produces the image. These devices are either CCD (charged coupled device) or CMOS (complementary metal oxide semiconductor).
SensitivityDesignated as the ISO, this controls the sensor's sensitivity to light. Keep in mind that the lower the sensitivity, the better image results you will generally get.
The camera’s white balance produces the most accurate color reproduction of the image being captured. Although the human eye automatically adjusts to different color temperatures, a sensor must be set to the appropriate color temperature. Most cameras are set by default to an Auto-White Balance setting which provides fairly good results; however, choosing the white balance manually should provide more accurate color rendition.
Depth of field
An image’s depth of field is the amount of the scene that is in focus from the extreme foreground to the most distant background. A large depth of field will render the closest objects to the most distant objects (infinity) sharp. A shallow depth of field will generally isolate the subject by leaving everything else in the image out of focus, which is sometimes advantageous in portraiture. Depth of field is controlled by the aperture.
Optical image stabilization is a feature of a camera lens that physically shifts the lens elements to compensate for movement caused by the photographer or the subject, which should produce sharper images. This feature is especially useful when taking images using a slow shutter speed or when using a telephoto lens. There is also electronic image stabilization on some camera bodies which actually moves the sensor to compensate for movement, but optical image stabilization usually produces much better results.
DSLR (Digital Single Lens Reflex)
A camera that diverts the light coming through the lens then records the image to the viewfinder until just before the image is captured so as to provide the most accurate viewing of your image. This is done by a 45° angle mirror which reflects the light up into a pentaprism and through the viewfinder.
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