A compound microscope can be used to observe or analyze microscopic objects or organisms that may otherwise be too small for the naked human eye to accurately observe. Compound microscopes differ from common light microscopes and stereoscopes in their design and overall function.
While common light microscopes contain one lens that magnifies the microscopic object or organism up to around 25 times, a compound microscope uses two lenses. Light passes through the microscopic object or organism to project the image in the first lens, referred to as the objective lens. This magnified primary image is then magnified further as it passes through the second lens, known as the ocular lens. The magnification of the microscopic object or organism varies. To determine the total magnification, the magnification of the objective lens is multiplied by the magnification of the ocular lens.
Most compound microscopes feature multiple ocular lenses, each with different powers of magnification, that can be rotated to change the total magnification of the microscopic object or organism. A compound microscope is useful for examining or analyzing microscopic objects or organisms that are too small for a common light microscope to magnify or too small for a stereoscopic microscope to magnify, which tends to magnify no greater than 50 times. However, objects or organism that are too large may not work well with compound microscopes and are more suitable for common light microscopes or stereoscopic microscopes.