In a camera, replacing the pinhole by a lens puts a lot more light into the image.
But now the film has to be at the right distance from the lens --- the camera must be focused and objects at different distance will not all give sharp images on the film..
Magnifier close to the object:
Little magnification.
Magnifier farther from the object:
More magnification.
Magnifier still farther from the object:
Still more magnification.
Magnifier at almost focal distance from the object:
Distorted image due to defects in lens.
Object at or beyond focal point:
No image.
Colors from chromatic aberration.
Notice that farsighted people wear glasses with converging lenses. The lenses have thin edges and the wearer's eyes are magnified.
Nearsighted people wear glasses with diverging lenses. These lenses have thick edges and make the wearer's eyes look smaller.
An astronomical telescope forming the image of a distant object. The image is inverted.
A compound microscope requires the object to be near the focal point of the objective lens. The image is magnified twice.
Astronomy: Telescopes