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.
In the video, Rob breaks down stops of light into its most basic – to the point of even removing all colour from the video so you can just concentrate on the brightness. He also illustrates the points using some tried and trusted analogies, but actually demonstrates them, rather than just talking about them, making things much easier to understand.
Rob also alludes to why it’s usually pointless to ask for settings when you see an image posted to social media. There are many different ways to shoot a good exposure of an identical scene, and you’re unlikely to ever find yourself in the exact same lighting situation as the photographer you’re asking. So the settings they used don’t really help you all that much on their own. You need to understand why those particular settings were chosen, too. And once you understand the principles of exposure, you won’t need to ask why.
If you’re still struggling to grasp how stops of light affect your exposure and your photography, it’s well worth a watch. And by the end, you should know everything you need to know about what a stop of light is and what it means for your images.