Hurter and Driffield

Hurter and Driffield is a historical concept related to photography.

When you take a photograph, you need to get the right amount of light onto your camera's sensor or film to create a good picture. But if you let too much light in, your picture will be too bright or overexposed. And if you let too little light in, your picture will be too dark or underexposed.

Hurter and Driffield were two scientists who figured out a way to measure how much light was needed to create a good picture. They discovered that the amount of light required depends on two factors: the sensitivity of your camera's sensor or film, and the amount of time the light is allowed to hit the sensor or film.

They created a chart that photographers could use to determine exactly how much light was needed for their specific camera and film combination, based on the ISO rating of their film and the desired aperture and shutter speed settings.

By following the Hurter and Driffield chart, photographers could ensure they were getting the right amount of light for a good exposure every time they took a picture. It's a bit like a recipe for baking a cake: if you follow the instructions carefully, you'll end up with a delicious cake every time!