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 the director 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?

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.

KEY LIGHT

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.

WHAT DOES GOOGLE SAY?

When I googled “High Key Lighting” I got a range of equally confusing descriptions 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 implies that low Key, being the opposite should 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 as many state that low key means overall dark. 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……     …….So usually, the shot has very little to no shadows present. 

Hmmm… OK, let’s think about that – if you have a key light that is stronger than the fill your likely to have lots of shadows, cast by the strong key light. The main role of a fill light is to fill in shadow areas, but if the key is stronger than the fill – shadows will be present and the image contrasty and generally high contrast is described as low key. Are you confused yet?

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? And what is unique or special about Low Key that it needs a special name instead of just being called high contrast.

The above image is of the painting Salome with the Head of John the Baptist by Caravaggio(1610). This image is generally considered Low Key. The mains source of light, the key light, appears to be quite strong, like sunlight through a window, appearing to come from above and to the left of frame.

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 indicates a key that is bright relative to the background.  The high contrast ratio between the bright key light and the rest of the scene  ensures the background appears as very dark relative to the foreground. But one thing remains, the key light is bright, not dim. The level of the key light is high, not low compared to the rest of the scene. So where does the term low key come from, how does a bright key get called low key?

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.

Here’s what I think…

I’d like to offer up an idea of where the term high key 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. The key lights would be up high, there would be low contrast and deep shadows were not desirable (because older TV cameras couldn’t handle high contrast).

At the same time in the world of cinema where a single camera is often used and high dynamic range was less of an issue, cinematographers were not afraid of casting shadows and using lights lower down on floor stands.

Typically TV lighting is described as high key and typically TV lighting uses key lights high up on a truss. Does the term high key stem from that typical approach to TV lighting with high up key lights, minimising shadows?

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. If you create high contrast using lights high up the shadows will be under the actors chins and eye sockets will be dark, not a good look. But move the lights lower, light more from the side and you get the look seen in the Caravaggio painting above, the key light is lower. Is this where the origins of these terms as – the hight of the key light?

high up, TV style key lights giving bright but flat look that works well for TV production while a lower, perhaps side on key light creates contrast across the scene in a more film like manner, creating a sense of depth due to the darker background?

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 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.