Handle all microscopes with extreme care while carrying them and returning them to storage. Hold a microscope by the base with one hand while supporting the metal support arm with the other hand. Drape a dust cover over a microscope when it is not in use. Store it in a dry, dust-free, acid-free environment, preferably an enclosed cabinet equipped with silica gel to prevent humidity.
Determine whether a microscope's eyepieces need to be cleaned by rotating each eyepiece in a circular motion while looking through it. Dust particles or stain residue will appear to move if they are present. Do not take an eyepiece apart. Check the objective lenses, the ones aimed at the specimen slide, by placing a slide down and moving it around. Any dust that moves will be on the slide. Dust on an objective lens will appear to remain stationary.
Clean all lenses with a dry piece of lens paper, using a circular motion. In most cases distilled water best cleans all surfaces. If necessary, use 70 percent alcohol as a cleaning solution on all lenses to remove stubborn residue, such as dyes and immersion oils, used to visually enhance the contents of a slide. Use a soft lens brush or air blower to remove particles of dust.
Adjust the focus knob on the side of the microscope, using the wrench provided. Place the wrench on the collar of the knob and twist it tighter or looser while observing a specimen to make adjustments.
Unscrew the illuminator lens housing to replace the light bulb, located on the base of a microscope beneath the slide stage. Only remove a light bulb after it has cooled sufficiently to touch. Screw in the new light bulb without handling the surface of the bulb, using latex gloves or a sheet of lens paper. Fingerprints and dust sticking to a bulb will shorten its life.