Applications of lenses: I. Cameras
The pinhole camera can produce a sharp picture if the pinhole is small
The amount of light striking the film is small. Very long exposure times are needed to make impression on the film
By using converging lens instead of a pinhole the exposure time can be greatly reduced.
Bigger lens better picture quality
Focus free cameras: can form sharp
images from objects far away (object
distance fixed to infinity, image
formed at the focal plane)
Auto focus cameras: can vary the
position of the lens relative to the
film--> can focalize all images on