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tube, and through the oculars. Each objective has numbers stamped on it. One of these numbers identifies the magnification of the objective (e.g., 43X). Objective lenses are usually named according to their magnifying power, as follows: 

scanning power 4X; low power 10X; high power 43X; oil immersion 93X or 100X 

A 2nd number on the objective, usually a decimal represents the numerical aperture for that lens; the abbreviation NA may precede the number. 

Note the magnification of each of the objectives on your microscope below. 

___________ ___________ ___________ ___________ 

The total magnification for each objective is calculated by multiplying the magnification of the ocular and objective lens on your microscope. On your worksheet below calculate the total magnification for each ocular/objective combination on your microscope. 

List the magnification for each objective on your microscope below. 

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Stage: The surface or platform on which you place the microscope slide is the stage. Note the opening (stage aperture) in the center of the stage. On some microscopes, the stage is stationary and has clips to hold the slide in place. On other microscopes, the stage is movable and is called a mechanical stage. Movement is controlled by 2 knobs located on the top, side, or bottom of the stage. Note the horizontal and vertical scales on the mechanical stage. 

Substage: The area under the stage, called the substage, may contain a diaphragm , a condenser , or both. 

Diaphragm:  The diaphragm  regulates the amount of light passing from the light source through the specimen and through the lens system of the microscope. By properly adjusting the diaphragm, you can provide better contrast between the surrounding medium and your specimen, thus greatly improving your image of the specimen. The diaphragm may be either annular or iris . An iris diaphragm  consists of a circle of overlapping thin metal plates. The lever that projects from the side of the diaphragm opens and closes these plates, thereby regulating the amount of light that enters the microscope. Most of you have a microscope with an iris diaphragm. An annular diaphragm  consists of a circular plate with holes of different diameters. You can rotate this plate to place the various holes in the light path, thereby regulating the amount of light that passes from the light source through the specimen. 

Condenser: The condenser  consists of a series of lenses that focus light onto the specimen. It is moved up and down by a knob at its side or by a lever projecting from the 

