| 5. Adjusting the microscope contrast | Basics |

| Remove the eyepiece and look into the eyepiece sleeve. You will see the aperture stop as illustrated above. Adjust the aperture iris diaphragm as appropriate.
|  | What is contrast adjustment?: Contrast adjustment is for adjusting the lightness and darkness of an image by using the aperture iris diaphragm. Specifically, the aperture iris diaphragm is used to adjust the numerical aperture of the illumination system; it effectively adjusts the resolution and contrast. If the aperture iris diaphragm is stopped down, the lightness and darkness of an image are enhanced, while the resolution declines. Since a microscope specimens generally have low contrast, it is recommended that the numerical aperture be adjusted to 70 to 80% of the NA of the objective. |
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