In this activity, students will observe images formed by a simple convex lens and compare cameras with and without a lens.
The first camera used a pinhole opening to let light in. Because the hole is so small, light rays that enter cannot overlap. This is why a clear image is formed on the inner back wall of the camera. Because the opening was small, a long time was required to expose the film sufficiently. A lens allows more light to pass through and still focus the light onto the film. Cameras with lenses require much less time for exposure, and the pictures came to be called "snapshots."