An arrow/disc object baffle lit from behind by a bright point source of light is used as the object, and various convex lenses are used to cast images of the key onto a screen. The effect of variation in focal length and object distance can be readily seen. Lenses with 10cm, 20cm, and 30cm focal length are provided.
Combinations of two convex lenses or a concave and a convex lens used together can also be demonstrated. Please request additional lenses if desired.