order to see contrast in the specimen, dyes such as stains are used. However, most stains tend to kill away the cells they encounter because they alter the functions of the structures in which they bind. 3. F ield of view means the extent of the visible image field that can be seen through the microscope. As the magnification is increased, the field of view is decreased. This relates to the fact that one should use the low-power scanning objective first because it has the greatest field of view which makes it easiest to locate a specimen. Depth of focus is how clearly the specimen or object appears to the human eye. As the magnification increases, the depth focus decreases. 4. Kohler illumination is setting up the light path of the microscope in order to get the best image possible. It is important to set Kohler illumination because the result is an evenly illuminated field and a bright image of the specimen without glare. To set Kohler illumination, first make sure that the condenser is fully raised and that the field diaphragm is closed; a small circle of light surrounded by a red halo should remain visible. Adjust the height of the condenser until the light seen through the microscope comes into sharp focus; the outline of the area of light should be polygonal in shape. Lastly, open the field diaphragm just enough so they the ring of light becomes its maximum size.
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- Spring '08
- objective lenses