Briefly explain the operation of a photographic lightmeter.

Question: Briefly explain the operation of a photographic lightmeter, including its sensor, measurement method, display, and application of measured values. Answer: A photographic lightmeter uses a light-sensitive sensor to generate an electrical signal proportional to the amount of light in a scene. It measures light using either incident or reflected methods and calculates the exposure settings based on this measurement and the user's chosen ISO and exposure levels. The calculated exposure settings (shutter speed and aperture) are displayed on a scale or screen, and the photographer uses this information to adjust the camera settings to achieve the proper exposure for the scene, preventing underexposed or overexposed photographs.