What is low key lighting?
Low Key lighting is simply a technique where you use shadow and high contrast to accentuate the shape of a subject.
It's a classic lighting technique that dates back to the Renaissance era. Rembrandt often used low key lighting, also known as Chiaroscuro, which means light-dark in Italian.
The interesting thing about low key lighting is that the classic artists such as Rembrandt all based their paintings on natural light. The irony is that today very few photographers know how to create low key lighting using natural light. Instead, most photographers resort to using complicated strobe setups, and the result can never look as good as a natural light low key portrait.
To create low key lighting using only natural light is extremely simple.
I took the above portrait of my son using only natural light. I didn't use any light modifiers, backdrops, background stands, light meters or strobes, and I didn't mess around with complicated lighting ratios either.
So how did I take a low key portrait in natural light?
1) The portrait above was shot in my garage in broad daylight.
2) I opened a side door and let light spill in into the garage.
3) I placed my son right at the edge of the light source, ensuring that the light came in from his left side.
4) Made the composition and took the picture.
How you can create low key lighting using natural light
The key ingredient of low key lighting is high contrast, and the best way to create high contrast light is to have a small light source. The smaller your light source, the harsher the light will be, and the more shadows you will have.
You don't need direct sunlight either. Light spilling in through a door or a window is all that you need.
An ideal place to try out low key lighting is in a garage, as they are usually predominantly dark places. All you need to do is to let light in through a small window or a door, and place your subject so that the light is coming from the side.
The smaller the window, the better. If you only have a large window, you can control the light and contrast with a curtain or by taping some cardboard to any windows to block off light where needed.
The golden rule for low key lighting is:
Smaller light source = more contrast and harder light.
Bigger light source = less contrast and flatter light.
How to black out the background using only natural light and no backdrop
Since you will be using a small light source, the contrast of the light will be very high, and as such the light fall off will be dramatic. If done correctly, you will not only have beautiful shadows to shape your subject, but the background will be completely black, even if your walls are completely white.
This results in a black background. No backdrops or photoshop needed.
More low key natural light setups
Here's a few more places you can use to create low key portraits using natural light and minimal to need for lighting modifiers or backdrops.
Low Key Natural Light Setup #1 : A Basement
Basements are usually dark places, and most of them have a small window, making this an ideal environment for a low key natural light setup.
Low Key Natural Light Setup #2 : A Tunnel
Have someone sit a few feet inside a tunnel, and play with the light falloff to create a low key portrait.
Low Key Natural Light Setup #3 : A Doorway
A doorway leading into a dark room is a great setup. Place your subject 3 to 5 feet inside the doorway and turn them sideways towards the door.
Low Key Natural Light Setup #4 : A window with Visor Blinds
A window with visor blinds allow you to control the light and is an excellent light shaping tool, available in almost all homes. Just make sure the rest of the room stays fairly dark.
Now that you know how to create a low key portrait using natural light, go ahead and try it.