Trying to explain the inverse square law is one of those topics that can cause every eye in the room to quickly glaze over. Thanks to its association with complex diagrams and equations, what’s actually a very important factor to take into account when attempting to light a scene isn’t as widely understood as it should be. Luckily photographer Karl Taylor has put together two videos that explain the law simply, and in short order.
All told, both videos add up to just 10 minutes, and once you start to see what he’s talking about, it’s really dead easy. Simply put, that while light power drops dramatically as it moves away from your subject, it also gets far more even. So if you’re lighting more than one person, a lamp in close proximity will mean that they’re illuminated very differently, where a further away one will be far more even. But you can also use this to your advantage to have your subject lit more brightly than the background.
With the pair of videos being so short, you really should be able to find the time to watch them and get a handle on how the Inverse Square Law of Light works, and actually seeing it in action is far more effective than starting at a diagram and formula, trying to wrap your head around how it would behave.