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. 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  EYEPIECE/ OCULAR X OBJECTIVE = TOTAL MAGNIFICATION ___________ ___________ ___________ ___________