A magnifying glass enlarges the image of an object by increasing the virtual angle at the eye when the object is viewed.

The angular magnitude of an object is the virtual angle at the eye. It is the angle the object subtends at the eye.
This angle determines the size of the image (apparent size) formed on the retina and hence governs the apparent size of the object

Convex lens	To focus the light of an object onto the film so that a sharp image can be produced.
Diaphragm	To control the size of the aperture and hence control the amount of light move into the camera.
Focusing Ring	To adjust the distance between the lens and the film so that the image is sharply focus on the film.
Film	Acts as a screen for the image to form onto it. Chemical on it will react when exposed to light and produce a photograph.
Shutter	Open when picture is taken to allow light move onto the film. The shutter speed is the length of time when the shutter is open. It control the amount of light move onto the film.
Aperture	Open when picture is taken to allow light move onto the film. The shutter speed is the length of time when the shutter is open. It control the amount of light move onto the film.

The film, which is normally kept in total darkness, contains a light-sensitive chemical called silver bromide.
When you press the camera button, a shutter in front of the film opens then shuts again, exposing the film to light for a brief moment only.
Different intensities and colours of light across the image cause varying chemical changes in the film, which can later be developed, ‘fixed’, and used in printing a photograph.
The image formed on the film is

SPM Form 4 Physics – Camera