Exposure and Controlling Exposure

Exposure and Controlling Exposure

• Some exposure related terms to help with the search
• CCD Sensor/Exposure
• A CCD sensor is a charge-coupled device sensor. It proved to be more than a computer memory chip, so it was developed for other uses like signal processing. It is more sensitive to light and is more advanced for imaging sensors.
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• Overexposed
• This means there is too much light.
  
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• Underexposed
• This is when there is not enough light and you can't clearly see what is going on in the picture.
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• Shutter
• A shutter allows light to pass through the camera for a certain period of time. This is used for a light sensitive sensor which captures the permanent picture or scene.
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• Aperture
• Aperture is a hole or an opening through which light is admitted. It determines the cone angle of rays coming through to the image plane. These rays can also pass through a lens, resulting in higher sharpness and focus. It is an opening where light can come through, and is adjustable inside of your camera lens. It can be adjusted to let in only the amount of light you want to let in in.
  

• Lighting (in terms of photography)
• Photographs are recorded light. We can control the light in photographs by chosing the light the picture is taken in, or by turning lights on or off, chosing the shade or direct sunlight, etc. A camera's light meter takes into account the different settings of the camera and tells what sort of exposure the combo plus the light will create on the film/sensor.
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• F-stop
• On a camera, there are things called f-numbers. These can be adjusted in steps called f-stops. Each stop has a corresponding f-number and decreases by half of the light intensity from the last stop.
  

• Bracketing (in terms of photography)
• Bracketing is the technique of taking more than one pictue of the same subject, using different camera settings for each. It is useful when trying to find the best shot. Many cameras also have autobracketing.
  
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• ISO (in terms of photography)
• The measure of how sensitive film is to light. Cameras which dont use film still have the same system that rates the sensitivity, and some cameras will adjust depending on lighting conditions
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• Metering:
• Metering is when the camera takes a light level reading from the environment of the picture, and selects the best combo of aperture and shutter speed. These can also be changed manually according to what the photographer wants, and there are multiple types of metering which can be set, such as overall metering, spot metering, and center weighted metering.
  

Spot metering- when the photographer is wants to get exactly what they are looking for this is used. IT is ideal is the subject has a long tonal rand and if the background is brighter than the foreground, or if something is too bright or too dark.

Center-weighted Metering- This is when the metering is weighted at the center of the picture and then averages for the rest of the picture.

Multi-Zone Metering- this is also called matrix, evaluative, honeycomb, segment metering, or esp. This is usually the default metering choice on most cameras. The camera will measure the light intensity on several points and combine the results to find the best setting for the picture.

• References:

http://hubpages.com/hub/ccd-sensors
http://en.wikipedia.org/wiki/Aperture
http://en.wikipedia.org/wiki/Leaf_shutter
http://www.lowel.com/edu/glossary/
http://en.wikipedia.org/wiki/F-number
http://www.answers.com/topic/bracketing
http://www.ephotozine.com/article/Beginners-Guide-to-Photography---Metering
http://www.all-things-photography.com/centre-weighted-metering.html