What primarily limits resolution in a light microscope?

The resolution in a light microscope is primarily determined by the wavelength of light used during imaging. Resolution refers to the ability of the microscope to distinguish between two closely spaced objects, and it is fundamentally limited by diffraction, which occurs when light waves encounter obstacles or apertures.

According to optical principles, the shorter the wavelength of light, the better the potential resolution because shorter wavelengths can resolve smaller structures. Visible light has a range of wavelengths; therefore, it can place limitations on how fine a detail can be observed. In practical terms, the resolution limit of a conventional light microscope is approximately 200 nanometers, largely due to the wavelengths of visible light (400-700 nm).

In contrast, other factors such as the type of objective lens, the brightness of the light source, and the quality of the eyepiece do play roles in image clarity and brightness but do not fundamentally affect the resolution limit as dictated by the physics of light diffraction. Thus, while these other components can enhance viewing quality, they cannot surpass the inherent limitations imposed by the wavelength of the light being used.