American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

The field and aperture diaphragms in a microscope control:

1. Image magnification

2. Color saturation

3. Focus and glare

4. Weight distribution of the scope

The correct answer is: Focus and glare

The field and aperture diaphragms in a microscope primarily control the amount of light entering the optical system, which directly influences focus and glare. The field diaphragm adjusts the illumination area, ensuring that light only passes through the intended area of the sample. This is crucial in achieving optimal contrast and preventing glare from extraneous light sources. The aperture diaphragm, on the other hand, controls the numerical aperture of the objective lens, which affects resolution and depth of field. Proper adjustment of these diaphragms can enhance clarity and minimize distracting reflections or glare, leading to a sharper image. In contrast, image magnification is controlled by the lenses themselves rather than the diaphragms. Color saturation is influenced by the type of filters or staining methods applied, and weight distribution is related to the physical design of the microscope rather than any diaphragmatic adjustments. The focus can be fine-tuned separately through the microscope's focusing mechanisms, rather than through the diaphragms.