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.
Lets look at the samples by Derrick.
- The first thing that is really obvious is the fact that the background is lighter when the light is further away. This is because the light-to-model distance is not that different from the light-to-background. When the light is closer, than the light-to-background distance is about double than the light-to-model.
- The other thing to note is the light falloff on the model. The closer the light, the harder the falloff
- Lastly, the closer you are, the softer the light, this is really obvious in the next set of photos