In adjusting the microscope light using Koehler illumination, which statement is true?

The correct answer highlights the importance of centering the condenser using the image of the field diaphragm. In Koehler illumination, proper setup is crucial for achieving optimal lighting conditions and improving image clarity. By centering the condenser based on the image of the field diaphragm, you ensure that the light is evenly distributed across the sample, which enhances both contrast and resolution.

This method of centering allows for uniform illumination of the field of view, minimizing potential artifacts and improving overall assessment of the specimen. This step is essential in microscopy as it directly influences the quality of the image that is obtained.

Other statements do not accurately reflect the proper techniques for Koehler illumination. For instance, adjusting the condenser to its lowest position does not provide an optimal focus and light path for observing samples. Similarly, removing the eyepiece to adjust the condenser height is unnecessary and can lead to misalignment, while closing the aperture diaphragm generally decreases the resolution rather than increasing it, as it leads to less light and a narrower angle of illumination. Understanding these key components helps ensure effective microscope usage in hematology practice.