Convex lenses (including magnification)

Convex lenses can produce an inverted image on a screen by refracting light. Rays parallel to the principal axis are refracted to the principal focus, located at the focal length of a convex lens. The image distance and size (magnification) depend on the power of the lens and the object distance. As the object distance decreases, the image distance and size both increase, until the object reaches the focal length. If the object is too close to the lens, the rays leaving the lens are parallel/diverging, images can't form on a screen.