After adjusting the microscope for Koehler illumination, how should light intensity be regulated when viewing with an oil immersion objective lens?

Using the oil immersion objective lens requires a specific approach to light intensity regulation for optimal viewing. When you are observing with this lens, the condenser plays a crucial role because it concentrates light onto the specimen, especially when utilizing the high numerical aperture of the oil immersion lens.

Adjusting the condenser optimally allows for proper illumination of the specimen while minimizing aberrations and enhancing image clarity. Conversely, while the rheostat can adjust overall light power, it may not offer the precise control needed when high magnification is achieved. The use of a neutral density filter can reduce light intensity but does not provide fine control suited for detailed observations. The light control knob also impacts overall light intensity but lacks the specificity required for high-resolution microscopy when using oil immersion. Therefore, adjusting the condenser is the best practice to ensure that the specimen is illuminated correctly, maximizing clarity and contrast for accurate analysis.