How a digital camera works

By Jakob Jelling

The digital camera is not something of a magic box that came out of the blue and made wonders! The digital camera is very much like the conventional analog camera, but the technology has been altered. It also contains most of the associated components that the conventional camera contains, like lens and a shutter for letting in light, however instead of reaching a photosensitive film, the light is made to fall upon array of image sensors or photosensitive cells. Much of the differences are like this, yet most of it still remains in oblivion for the ordinary people. And it order that the digital camera gets its true respect, it is necessary to explore these areas of truth and reveal them in light.

Looking a bit more in details about the working of the fantastic device, the digital camera. As a continuation of the above lines, it can be further investigated that the sensor array is basically a microchip about 10 mm across. Every image sensor is a charged-couple device (CCD) converting light into electric charges, and is essentially a silicon chip used to measure light. These charges are stored as analog data that are then converted to digital via a device called an analog to digital converter (ADC). Over the chip are present a collection of very small light-sensitive diodes, named photosites, or pixels that convert light (or more scientifically, photons) into electrical charges called electrons. The pixels are very much light sensitive, therefore with brighter light striking them, produces greater build up of electrical charges. Each 1000 array receptor creates 1 pixel, and every pixel corresponds to some information stored. The light enters the digital camera via the lens, which is the same mechanism as the conventional analog camera. And this light hits the CCD when the photographer presses the shutter button. The shutter opens and thereby illuminates every pixel, however with various intensities.

Taking a look apart, it can be observed that quite a few digital cameras use CMOS (meaning complementary metal oxide semiconductor, a technology of manufacturing these microchips) technology based microchips as image sensors. The basic advantage is that the CMOS sensors are appreciably cheaper and simpler to fabricate than CCDs. Another great advantage from CMOS sensors is that these take very less power compared to other technology, which adds up to the fact as to their extensive use, and can thus even support the implementation of additional circuitry on the same chip like ADC, some control units etc. Thus it can be stated that CMOS technology based cameras are small, light, cheap and also energy efficient, yet at the cost of some amount of image quality.

However the common trend remains that all cameras of the mega pixel range and higher up use CCD chips instead of CMOS. This is because of the fact of picture quality only, leaving aside the price differences.

This is basically the fact about how digital cameras work! Having known this much difference would not come in the photographing expertise of the users, but it always feels a kind of satisfaction on understanding the inner depths of a device that is so close to the eyes!


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