By Max and Zoe

Light reflects off all objects that you see around you. The light enters the camera through a lens that focuses the light onto the sensitive plate (usually a film, or sensors in a digital camera). The plate captures the image and it is processed either chemically, if an analog camera is used, or by downloading the image to a memory card or computer.

When light waves enter a piece of glass at an angle, one part of the wave will reach the glass before another and so will start slowing down first. This was explained in a movie that we watched in class. In a normal converging convex lens (which is found in the average camera) one or both sides of the lens will bend outwards. This will make the light bend towards the centre of the lens.

This reverses the path of light from an object. As an example a candle is in a room. The candle is spreading its light all over the room. A converging lens will take the light rays from the candle and redirect them (focus them) so that they are all converging back to one point. At the point where the rays converge, you get a real image of the candle.

The focus of a camera depends on the angle that the light is coming from. The angle of light entry changes when you move the object closer or farther away from the lens. The lens only bends the light beam to a certain total degree, no matter how it enters. Consequently, light beams that enter at a sharper angle will exit at a more obtuse angle, and vice versa. The real image of a closer object forms farther away from the lens than the real image from a more distant object.

If the light does not hit at the right angle the image will be some what blurry So when you are twisting the zoom lens in an old fashioned camera you are moving the magnifying glass further or closer from the film.

The final part of a camera is the way that the photo is processed onto film. When you click the shutter, you have frozen a moment in time by recording the visible light reflected from the objects in the camera's field of view. In order to do that, the reflected light causes a chemical change to the photographic film inside the camera.

Click view movie ‘Refraction and Images’ Heinemann Science Links 3 work