Figure 2-5. Compound microscope.
16 mm (10X)
4 mm (43X)
1.9 mm (97X)
Magnification is increased in practice by using a higher power objective. Most
microscopes are equipped with a revolving nosepiece, and selection of an objective
lens is done with ease.
(1) Correct illumination of the object under study is an extremely important
detail. Incorrect lighting of the object can lead to inaccurate results and conclusions.
Correct illumination can be obtained from a concave mirror or substage light.
(2) Illumination entering the microscope can be central or oblique. To
obtain central illumination the light from the source must be reflected from the mirror
directly into the microscope tube. Oblique lighting must be avoided because an object
in the center of the field will sway from side to side when the fine adjustment is rotated.
Oblique light is usually no problem with substage illuminators.