camerathunder.com

All that talk about f/stops, shutter speed, and ISO settings may seem irrelevant to your digital camera, but it’s not—all cameras use these concepts, even though they’re sometimes disguised fairly well. The main difference between a digital camera and a chemical film camera, of course, is the fact that digicams don’t use film. That means you never load anything that has a specific ISO value into the camera. So how does the camera actually work? Simple. When light enters the camera at the moment of exposure, it doesn’t hit light-sensitive silver halides that are fixed in a chemical broth. Instead, the light hits a computer chip called a charge coupled device (CCD). The CCD is light sensitive, and each of its many pixels register changes in light just like the film’s many grains of silver react individually to light. In other words, the silver grains in film and the pixels in a CCD are essentially the same thing. They contribute to your picture in the same way, and both are the smallest components that make up your picture.
The CCD makes a picture by noting the variation in light rays that travel through the camera lens. The CCDs pass this information on to the camera’s microprocessor in the form of varying electrical charges. The image is transformed into digital bits and stored on a memory card. Your camera’s CCD functions like the film in a 35mm camera, except that it differs in one important way—you can’t swap the CCD out of your camera and insert one with more light sensitivity for low-light photography. The CCD is a permanent part of the camera. Camera makers understand that you might need to change the camera’s light sensitivity on occasion, though, and that’s why many cameras can have their ISO rating “adjusted” on the fly, whenever you want. In essence, what this does is allow you to “turn up” or “turn down” your camera’s sensitivity to light.

You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.