What is a stop of light? Essentially, it’s a relative quantity of light. Either half or double of a pre-existing amount. But what does that really mean? And why does it take Rob Hall 8 whole minutes to explain it? Well, that simple concept comes with a lot of implications in photography, and it applies to everything from our ISO, aperture and shutter speed to flash power, flash distance, neutral density filters and more.
Understanding what a stop of light is and what it implies are vital for creating good and consistent exposures in photography, and it’s one of its most basic principles. If you don’t understand it, it can be difficult to figure out what problems might be occurring when you shoot an image and it isn’t what you expected.