The Inverse Square Law pops up in photography often, particularly for users of flash or continuous LED lights. It’s a topic that still confuses a lot of people, although the mathematics of it can be translated into easy-to-understand practical terms. In this video, from ZY Productions, we get to see both explanations to satisfy both the maths geeks as well as those who just want to know what it means in the real world.
The inverse square law (ISL) is one of those principles of photography that drives people crazy. It’s a fairly simply concept that’s broken down into a rather confusing sentence. It states that the intensity of an effect such as illumination or gravitational force changes in inverse proportion to the square of the distance from the source. That, to most people means absolutely nothing.
So, in this video, photographer Joe Edelman is here to explain it in straightforward terms. In his usual way, Joe has lots of diagrams and practical examples to illustrate what it’s all about. The ISL can be a difficult one to wrap your head around at first. Once you understand it, though, it all makes complete sense. You’ll wonder how you ever got on without knowing it.
In this blog post, I would like to share some insights with you regarding the connection of aperture and inverse-square law of light as well as their effects on light fall-off. I’m going to be using Set.a.Light 3D to demo some of the things, but light behaves exactly the same in the real world. Let me ease you into this topic by explaining the aperture first.
When I started to use artificial lighting, The Inverse Square Law was my nemesis. Not only it is not intuitive, but it is also not linear, and visualizing how a strobe distance from a subject will impact the photo is not trivial to say the least.
Photographer Derrick Bias shared a few priceless photos that show the exact impact that moving a strobe away fro ma subject has.
One trivial effect, of course it the fact that less light hits the model, but light fall off, background to model illumination ratio and overall contrast also play a part in this game. While I encourage everyone to take the time to learn The Inverse Square Law, and its impact on your photos these photos will provide an instant reference point if you are just starting out.