What adjustments should be made when calibrating a photographic light meter?

When calibrating a photographic light meter, both total darkness and the brightness of the source must be considered. Adjustments for total darkness are crucial to ensure that the light meter correctly reads zero light, which serves as a baseline for accurate measurements. Without this calibration, the meter may react to residual light, leading to incorrect exposure values.

Furthermore, adjusting for the brightness of the light source is essential to calibrate the meter to ensure it provides accurate readings across different lighting conditions. Different light sources can have varying intensities and color temperatures, which affect how the meter interprets light exposure.

By accounting for both conditions during calibration, the photographic light meter can deliver precise and reliable readings, enabling photographers to achieve the desired exposure in their images.