Digital Camera & Film

Most of you would know how a film camera takes a photo. Its part of almost every physics text in school/college. In brief, the digital camera works on the principle of the pinhole camera. Light enters the opening of the camera, goes through some transformations, if there are lenses, and then finally falls on the film that is there in the camera. The film is coated with a chemical like Silver Iodide which reacts to light. Depending on the intensity of the light that strikes its surface a sort of a shadow is formed on the surface of the film. Where the intensity of light is more, there the reaction is greater and the surface of the film becomes darker. At places where the light is not present, the film doesn’t react and is stays light. This is why the film contains the ‘Negative’ of the image you are capturing. This negative is converted to a positive image when it is developed in the darkroom.

Now we have digital cameras whose main advantage is that there is no need to buy and keep replacing film. So how does the image form on the digital camera? These use a sort of digital film. It is a sophisticated IC chip. This chip contains millions of small photo sensing pixels and this is what records the image. Each pixel captures the intensity of the light falling on it. Another important part of the digital camera is the image processing chip. This chip receives the image from each pixel on the chip and composes this to form the actual image. How the sensor is actually fabricated and how it records the images is a advanced topic and we will have a look at this in a later stage. For now, you have to understand that the sensor and the image processor together is able to capture the light that falls on its surface and record this on the memory card that comes with the camera. This is how the digital camera has come to replace the film camera.