At their most basic level, Cameras, both the Single Lens Reflex Camera and Digital Camera simply involve using a curved piece of glass or plastic (lens) to conduct a beam of light bouncing off an object, and to redirect this light in such a way that a real image is formed-an image that looks exactly like the object in front of the lens. The only difference between manual or conventional film cameras and digital cameras lies in how these basic processes are accomplished.
In film cameras, after the lens has formed an image of the object, the image is then focused on and recorded by a chemically-coated piece of plastic, the film. Then the film is chemically processed, after which the image is printed onto a photographic paper, and then we have pictures that can then be stored in our photo album or distributed to friends as desired. But digital cameras take a shorter route to achieve the same result stated above.
Digital cameras are a part of a larger breakthrough that we’ve witnessed in consumer electronics over the past twenty years-the wholesale conversion of analog information into digital information. When we really get down to it, CDs, HDTV, DVDs, MP3s, DVR, etc are all built around the principle of converting fluctuating waves into bits of ones and zeros. Conventional cameras depend fully on chemical and mechanical processes-you can actually operate them without electricity! But the digital camera presents a paradigm shift here: it has a built-in computer that records images electronically, and must thus be powered by electricity.
Just like manual cameras, digital cameras also use the lens-actually series of lenses-to focus the light from an object to form an image. But unlike the manual camera, the image formed by the lens in a digital camera is not focused onto a piece of film to be recorded. Instead, the image is focused onto a semiconductor device that is capable of recording light electronically. A computer is then used to break down this electronically-recorded information into digital bits of data. Let’s now take a closer look into the inner workings of a digital camera.
Included in a digital camera’s built-in computer is a sensor that converts light into electrons, or electrical charges. Depending on the camera’s manufacturer, this image sensor may be either a Charge Coupled Device, (CCD), or Complementary Metal Oxide Semiconductor (CMOS). To be honest, notable differences exist between these two types of sensors (i.e. CCD and CMOS). But they perform the same basic function in a digital camera-converting light into electricity. Hence, for the purpose of understanding how a digital camera works, we’re going to think of them as identical devices.
And somewhat like the film cameras, a digital camera also has to control the amount of light that reaches the sensor. Yes, it also makes use of the Aperture and Shutter Speed. But these are mostly automatic and can be reset electronically. Now, a digital image is just a long string of 0s and 1s. It is the sensor that reads and interprets the values of these digits as contained in the cells of each recorded image.
Next, another device known as Analog -to-Digital Converter (ADC) turns each recorded pattern of light (pixel values) into digital value by measuring the amount of charge at each cell, and converting that measurement to binary form. Remember we stated earlier that every digital camera has an in-built computer? Now, a processor therein interpolates the data from the different pixels to form natural color. For the majority of digital cameras equipped with LCDs, it is possible at this stage to see the image that has just been photographed before deciding to print it.
At this stage the information is stored in some form of memory within the camera-all digital cameras are equipped with a number of storage systems, most of it removable storage devices. We can consider these as forms of reusable, digital films. And because pictures take up lots of storage space, most digital cameras use some sort of data compression to make the files smaller. A card reader can then be used to transfer the information stored therein (i.e. photographic images) to a computer for further usage.
The processes described above sure sound complicated, right? Don’t worry. In practice, it all happens so effortlessly that we barely take note of anything while using a digital camera-which is what makes it fun to use: the ease and the speed. Imagine that you want to e-mail a picture to a friend. With conventional cameras, you’ll first have to capture the image, process the film, print the picture, and then use a scanner to capture the picture again and record it as pixel values for onward e-mailing to your loved one. But with a digital camera, the picture is automatically broken down and recorded as pixels ready for e-mailing. That’s the fun. Plus, you also get to view the image, live, before setting to print!