Methods in Microbiology Methods in Microbiology Bact.
Lenses serve as prisms and bend light to a focal point.
Lenses focus light at a focal point F, the distance from the lens to the focal point is called the focal length. Dra w a lens on the board. Our eyes have a focal length of 25 cm and cannot view objects that are much closer than that. This limits what we can see to about 0.2 mm. Draw two lines on the board and bring closer together.