How do Cameras relate to our Physics Class

Adriana C. Santos-Rodríguez

Have you ever wondered how a camera works? It’s pretty amazing to see what it can do, but how does it do it? This very popular device used in the 21st century, were even cell phones have tiny ones.  The basic principles on how a camera works are learned in our very own Physics class. A digital camera takes light and focuses it via the lens onto a sensor made out of silicon. It produces the photos by converting light particles into electricity. The basic technology that makes all of this possible is not very complicated. A camera is basically made of three basic elements: an optical element, a chemical element and a mechanical element. As you can see the only trick to making a camera is combining these elements to create this wonderful device. In this article, we will restrict our information on the optical element, because it is of more relevance to the class. The optical component of the camera is the lens. Like we studied in class, a lens  is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. At its simplest, a lens is just a curved piece of glass or plastic. Its job is to take the beams of light bouncing off of an object and redirect them so they come together to form a real image, an image that looks like you can see on the lens. The lens slows down the light, as we know light travels at different speeds depending on the medium, in the air it travels faster than when it reaches the glass of the lense, therefore helping us capture the image. The light waves enter the lens at an angle, and slowly the wave will reduce it speed. This angle causes the light to bend in one direction, and it causes it to bend again when exiting the lens. This causes that parts of the light wave enter the air and speed up before other parts. In a double convex lens, the light will bend when it exits as well as when it enters. The convex lens takes the light rays and redirects them to the light source, creating a real image where the light rays converge.  The nature of this real image varies depending on how the light travels through the lens. As we learned in class, and like we proved in the physics lab, the angle of light entry changes depending on how far or how close the object is from the lens. But we need to remember that the lens can only bend the light beam to a certain degree, no matter how it enters. Also, we need to remember that from a closer point a light beam converges at longer distance from the lens. To make more clear, the real image of a close object forms farther away, than the one of an object that is at a longer distance. This is what we cause when we turn to zoom in and out with the lens of our cameras to focus on a specific object. Then to capture the image the camera creates a chemical reaction using the film (old cameras) or by using electricity (digital cameras).