The microscope was invented in the late 1500s/early 1600s and originally had a length of 6 feet. Key early developers included Hans Janssen, Zacharias Janssen, Anthony van Leeuwenhoek, and Robert Hooke, who made improvements to lens design and magnification. The modern microscope uses convex lenses in the objective and ocular to bend and magnify light, with magnification determined by multiplying the objective and ocular powers. Proper use and care of microscopes involves starting at low magnification, using adjustment knobs carefully, and cleaning the microscope with soft cloths only.