You’ve probably heard the term High Key as well as Low Key a million times in the world of photography, video and film. But where exactly does the term come from and what exactly does it mean?

I had to ask myself this today when during a discussion about a future shoot it was stated that we would shoot some low key scenes. But I wasn’t really 100% certain in my own mind what that meant. Does it mean dark? Does it mean a low key light level (relative to the background), or is it the positioning of the key light?

Look, this isn’t a term that’s new to me, I’ve come across it many times, but I’ve never particularly liked the term because it always seems to mean slightly different things to different people, so you can never be sure what they really mean.

First of all what is a “key light”? Generally the key light is the main source or most important source of light in a scene. I don’t know the origins of the term or how long it’s been in common use, but it seems to be a relatively new term specific to photography and video.

When I googled “High Key Lighting” I got an equally confusing description of what it is. On Wikipedia for example, high key is described as “High-key lighting is usually quite homogeneous and free from dark shadows”. OK, so that would mean low Key to have dark shadows and not be homogeneous – ie. high contrast. And this doesn’t really seem to match what a lot of people consider low key to be. Elsewhere I came across all sorts of frankly bizarre definitions of high key such as….
High-key lighting creates a clean focus on the center of attention and then in another article it stated that it means that when you use a high-key setup, the key light is stronger than the fill lights. but then went on to say So usually, the shot has very little to no shadows present. Hmmm… how can you have a key light stronger than the fill and then also not have shadows?

Well, at least I know I am not the only one not entirely sure what these terms that get thrown around all over the place truly mean. Let’s face it if I said I was going to make my shots “contrasty” or with “deep shadows” or perhaps “flat” I am sure everyone would be on the same page.  But “Low Key” what does it mean? Is it just dark? Is it contrasty? Is it flat? 

The above image is of the painting Salome with the Head of John the Baptist by Caravaggio(1610).

Clearly the main light, what we would normally call the key light is the brightest source of light and it must be relatively bright.  Let’s imagine for a moment that the ratio between the Key light and rest of the scene is 8:1. This ratio is often quoted as the minimum for low key and suggests a bright key relative to the background. As light and contrast is relative you could actually achieve a similar look in a bright room – provided the key is 8 times brighter than everything else and then you stop down or add ND to the camera to bring your exposure down to a reasonable level. The high contrast ratio will ensure the background would be very dark compared to the foreground. But one thing remains, the key light is bright, not dim. It is high, not low compared to the rest of the scene. So where does the term low key come from?

The term Low key has been used in music for a very long time to mean a quiet or deep tone, but I don’t think the image above could be called “quiet” and low key lighting doesn’t always mean very dark, it normally means high contrast and often includes very bright highlights.

I’d like to offer up an idea of where the term actually comes from when applied to photography and video: TV soap and episodic multi-camera lighting. Perhaps when we use the term high key today it is a discombobulation of different concepts and terms and that is why there is often confusion. 

Traditionally daytime episodic TV has always been shot quickly using multiple cameras. To make this possible the lights are normally up above the set suspended from the ceiling on some form of grid or truss system. This ensures that the lights are not seen by any camera whichever angle they are shooting from. In addition the lighting will generally not cast deep shadows so that you can shoot from multiple angles without issue.

High Key isn’t about how bright the scene is, you could be shooting a night scene. But the lights are up high, above the set and the lighting will be free of strong shadows. So High key isn’t about brightness, it’s about contrast and also the key light position, up High so you don’t end up with cameras shooting directly towards the light.

The the opposite of high key will be low key where perhaps the key light is creating a lot more contrast, where the key is brighter than the fill and not only brighter, but perhaps more commonly at a lower height so that the low key light casts shadows across the scene to create a sense of depth rather than just on the floor. Arguably this doesn’t mean the scene will be dark, just that there will be contrast between the key light and the rest of the shot.

So, in summary:
High Key = Uniform lighting of both foreground and background with minimal shadows. But could be either overall bright or overall dark, often with the key light(s), of which there may be many, placed high above the scene/set so you can shoot the scene from any angle.

Low Key: A relatively bright key light so that there is contrast between the key lighting and the rest of the scene/shot. Overall the scene may be bright or dark, but it will have high contrast and shadow areas. Possibly the key light will be at a lower level so the low level key light  will cast shadows across faces and objects to provide depth and modelling.

So many descriptions of High Key and Low Key simply refer to the overall brightness of the scene, this is not correct. A High Key scene can be dim and a low key scene MUST contain areas of great brightness in order to have the contrast associated with low key. All too often stating that the term High Key comes from the use of a bright key light over simplifies the situation to the point where it is no longer clear what is meant because to create nice looking Low Key you will will often need a bright key light.

Please discuss in the comments.