One of the most crucial things any photographer working with artificial light needs to learn is the inverse square law, which has deep consequences on how light behaves and the look of your images. If you are new to working with artificial light and want to learn the inverse square law, check out this excellent video tutorial that will show you what you need to know.
Coming to you from Daniel Norton Photographer, this great video tutorial will show you the ins and outs of the inverse square law. Besides the fact that it has deep impacts on the technical and aesthetic aspects of your images, it is important to learn because photographers need to understand how light's behavior deviates from intuition. Human brains generally assume things behave linearly and base estimations on that, but light intensity decreases with the square of distance, which means our intuition will lie to us. This is why it is so important to know its true behavior to override that incorrect intuition. Check out the video above for the full rundown from Norton.
If you would like to continue learning about how to light a portrait, be sure to check out "Illuminating The Face: Lighting for Headshots and Portraits With Peter Hurley!"
There must be a better way to explain this, maybe with constant light not a ttl flash, and then using full powered flash at the end...huh?
I used to understand it.
Basically the falloff is greater the closer you are to the light source. So if the subject is very near the light the background will be relatively much darker. If the subject is near the background and away from the light the difference between the subject and the background will be much less so the subject and background brightness will be more similar. Obviously to light the subject when she’s further away the light will need to be brighter (he just used TTL so he didn’t have to keep adjusting the light manually - if he kept the light constant she’d have got darker the further she was from the light and that wouldn’t have looked too good!) It’s easier I think to think of it just in terms of the subject. If the subject is very near the light then the side of the face further from the light is quite dark. If the light is a long way from the subject then both sides of the face will be pretty evenly lit.
Light is not difficult to understand he said all he needed to say in the first few sentences.
Light drops of quickly! Nuff said.
I have always thought the "you must know and follow the inverse square law" thing to be a weird photographer flex.