9/23/2011

Difference between Analog and Digital Cameras.

By Dmitry Vasenyov


The digital photo cannot be comparable to the analog photo (that uses slides or negatives). From a technological standpoint it is rather closer to the videography that obtains an image at any given time.

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

To put it simply, the analog camera consists of the system of lens, aperture and shutter; the light, having focused in the objective lens, passing through the aperture at a time until the shutter is open, falls on a photosensitive film. Under the action 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 various principles of work. Both cameras have the system of lens, diaphragm and shutter, but recording methods differ drastically. The digital camera stores photos in digital format on the special media. Closer examination helps to understand the difference in working methods.

The heart of a digital camera is CCD (charge coupled device) hidden behind the aperture and consists of a photosensitive semiconductor elements made from a lot of silicon diodes. When the light reaches the CCD, it charges every element - pixel 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 larger than the nail on the finger, and contains some few millions of light-sensitive diodes, placed on the surface of the matrix in the form of columns. So far as the matrix responds only to the brightness, the digital camera is capable to reproduce only black and white picture. Notwithstanding, there is a way to capture all the colors of the picture by applying various color filters in the objective-glass: red, green, blue, or a combination of colors that gives the most realistic picture.




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