By Dmitry Vasenyov


You cannot compare the digital photo with the analog one (that applies slides or negatives). From a technological perspective it is rather closer to the video filming that gets an image at any one time

Let's take a look at how the analog camera operates.

In simple terms, the analog camera consists of the system of lens, aperture and shutter; the light, having focused in the objective-glass, passing through the diaphragm at a time until the shutter is open, falls on a photosensitive film. Under the influence of photochemical processes the image is "recorded" on film and in the future it can be restored by developing.

Though digital cameras look like as analog, they apply varied principles of work. Both cameras have the system of lens, aperture and shutter, but recording principles differ drastically. The digital camera stores shots in digital format on the special media. Closer examination helps to understand the difference in operational methods.

The heart of a digital camera is CCD (charge coupled device) hidden behind the diaphragm and consists of a photosensitive semiconductor elements made from a variety of silicon diodes. When the light reaches the CCD, it charges each of the elements - pixels individually.

This charge in the future corresponds to an electric pulse, and in such a way we obtain the data in digital form about luminosity of every pixel. Forasmuch as it is impossible to record all information about the whole picture, but in future it is treated by software to recover lost data and recorded on magnetic media. Thereby, the digital photography is a combination of CCD sensor, software and memory cards, replacing the film in the analog camera.

CCD matrix is not greater than the nail on the finger, and contains several millions of light-sensitive diodes, located on the surface of the matrix in the form of columns. Since the matrix responds only to the brightness, the digital camera can produce only black and white. However, there is a way to capture all the colors of the image by using different color filters in the lens: red, green, blue, or a combination of colors that gives the most realistic picture.




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