Low key is just the opposite of high key; the tones are all darker, made up of medium to dark grey values and some black. This light can be higher in contrast or also low in contrast using darker tones. Here is an example of a low key portrait that I shot for a non-profit book project on notable women in the Pacific NW which included writers, politicians, artists, dancers, etc.
The first step was to create the background and I began by painting the wall medium grey. Next, I used a sponge and dabbed it in white paint and “splotched” it all over the wall followed by doing the same thing with black paint. When out of focus this creates a pretty cool texture. I then threw a canvas on the floor to cover it.
For lighting I used an extra large light box on camera right and a grid was hitting her face. The idea was that the grid is the key light and the light box is also a key light but weaker so it acts like a key light that is filling in. The technique is to get a bright face and have the light gradate down her body and get weaker as it goes.
I also used a cutter card. A cutter card is a black piece of foam core (or something else) that is either huge or small. The purpose of a cutter card is to block light that is hitting the subject from hitting the background. So you place the cutter card between the key light and background and slide it in and out until you have the light blocked satisfactorily. If you look at the darker right side and shadow on the floor that is from using a cutter card. The last light was a grid on the wall. I then completed my technique in the darkroom with adding some diffusion.
The term High Key addresses the technique of creating photographs that are all light in tone or in other words, a very short tonal range. Key is the term describing tonal value. Low key is darker in tone. High Key is often very flat in lighting to avoid shadows, which are dark and thus lower in key. To achieve a high key look you need to consider the tones of your subject and your background. A portrait of a woman wearing white against a white background and soft lighting would make a nice high key portrait.
This portrait of a ballet dancer is an excellent example of high key and motion. I used a white seamless background and she wore a very light toned outfit. I used two large soft umbrellas, one above the other, on camera right about, 4:00 o’clock and another large umbrella above camera for fill. The fill was set at -1/2 below the key light. I then accentuated the effect in Photoshop by making the background pure white.
This image from the previous examples can also be considered high key. The tones are mostly bright with minimal shadows. This was achieved with the large Octa Dome light.