How One Background becomes white, grey or black on demand.
Some of my clients believe its magic. I take a white background then turn it any shade of grey or even black that I want. Or rather that they want. Even some photographers do, but today I will show you how easy and simple it is to get just that, on demand.
Silvia was in for her biz card head shot. She brought with her a sample of images one was starkly white, a jolt with her dark skin the other was a soft shade of grey, which she liked. That was what she wanted and hoped I had a matching grey background for her.
I don’t have any grey backgrounds.
Here is the concept to make this work. A white background is only as white as the amount of light that falls on it relative to exposure. You can make a black background white by blasting light on it and overexposing it. For the white background, it is a ratio of light to exposure. If your main light is f8 and the light on your background is f4, the background will be grey. The greater the difference is in exposure, the darker the white background becomes.
Going the other way, if the background is brighter than the subject light, it will become a pure white background.
To get a white background pure white, you just need one stop to 1.5 stop of light greater on the background than on the subject.
You can set this up by lighting the background separately from the subject. The subject needs to be far enough in front of the background so the light used on them does not fall on the background. With this approach you can introduce gelled lights to make the background a repeatable and predictable color.
Dean Collins taught this approach stunningly well.
For my approach I was using one light. A large softbox not aimed at the subject. The natural fall off of the light evenly lit the white background. By moving my subject and light closer to the background I was able to make the background any shade of grey I wanted. Once Silvia saw the shade she liked, we were good to go.
Pull her and the broad light source away from the background, it will eventually go black.
The final touch was a reflector to light up her dark side of the face. Same magic, pull the reflector in or out to control the amount of fill.
So lets look a little closer at some of the elements to make this work.
Use a large softbox. It puts out an even wall of light with a broad drop off of the light. It will give you an even light falling on both the background and your subject. Place it a several feet from your subject but aim it across her rather than aimed at her. You can slightly tweak it towards her or away for some critical control.
If you don’t have much space you can angle the background so it aims away from the light source. This will cause the fall off the light to happen faster. By aiming it towards the light it will become brighter faster. Because it is a flat surface with no reference it all looks the same to the camera.
Work with a long lens. It has a narrow angle of view for the background so your background coverage of light or background width does not need to be much. For my shot with Silvia it was only a a4 foot wide gator board. The bonus is the longer lens will make your subjects look better.
A light meter will make this setup happen faster with more repeatable control of your light. Does not need to be expensive or exotic, just measures the flash.
Once you start to play with this you will be amazing clients as well, plus saving a bunch on backgrounds.
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