photoconductive exposure meter

A photoconductive exposure meter is a device used in photography to measure light intensity and determine the correct camera settings for exposure. Unlike older photovoltaic meters that used selenium cells to convert light directly into an electric current, photoconductive meters utilize a light-sensitive element, often a silicon photodiode or a cadmium sulfide cell. This element changes its electrical resistance based on the amount of light it receives, and this change is measured by a circuit to indicate the light intensity.1

These meters are crucial for achieving a properly exposed photograph, ensuring that the image is neither too dark nor too bright. They can be built into cameras or used as separate handheld devices. Handheld meters can measure both incident light (falling on the subject) and reflected light (bouncing off the subject), offering more versatility than the reflected-light-only meters typically found within cameras.12