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How Does a Digital Camera Work?

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To understand digital cameras and photography, it would be good to know how digital cameras work so when you are looking for one, you’ll know the terms involved and what to look for. Digital cameras are basically like regular 35mm film cameras. They have a lens, aperture, and a shutter. The lens brings in light from what is being photographed into the camera so it can produce an image of it. The aperture is a hole that can be adjusted smaller or larger to control the amount of light entering the camera. The shutter opens and closes to control the amount of light that will enter the camera.

What makes a digital camera different from a regular 35mm camera is the way the image is captured. Instead of using film, digital cameras use an image sensor, which is usually a charge-couple device (CCD). If you look at the surface of the image sensor, you will more than likely see a grid that will contain millions of photosensitive diodes called photosites. Each photosite is responsible for capturing one pixel.

When you press the shutter release button, a metering cell measures how much light is coming through the lens and adjusts the aperture and shutter for the correct speed to produce the right exposure. As soon as the shutter opens, immediately each pixel on the image sensor records the brightness of the light that hits it. It does this by accumulating an electrical charge. Pixels that have captured light from highlighted areas are highly charged while those pixels that record less light have low charges. After the shutter closes, the charge that is on each pixel is measured and converted into a digital number. Each number is used to reconstruct the image based on the brightness of the light, and the color from each pixel.

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