Spark image

Images produced by a thin convex lens

This animation shows how the image size and distance depends on the object size and distance. As the object approaches the principal focus both the image distance and image size get bigger. The animation stops before the object actually reaches the principal focus.

The magnification of the lens is simply equal to image distance/object distance. Notice that the image gets both longer and fatter - magnified in two dimensions.
© Keith Gibbs 2007