In this video and article, I’ll explain, in simple English, what Contrast Ratio means, and how it affects high and low key lighting styles.
First, watch the video:
Contrast ratio as I talk about it always refers to a face.
Contrast ratio is the difference (in stops) between the brightest (key side) and darkest (shadow side) portions of a face.
Note: Many photographers use contrast ratio with different math but for cinematographers that’s useless. I always measure and talk about contrast ratio in stops. E.g., when I say 2:1, I mean the contrast ratio is two stops to one.
High Key and Low Key Lighting
High key and low key lighting refers to the contrast of an entire scene, not just the face.
When a scene has a high contrast (great difference between the brightest and darkest portions of the face), we say the scene is low key. Lighting used to get this look is called low key lighting. Here’s an example:
On the other hand, when a scene has a low contrast (small difference between the brightest and darkest portions of the face), we say the scene is high key. Lighting used to get this look is called high key lighting. Here’s an example:
Exception: A moody scene with low contrast is not usually called a high key scene in cinematography:
Not all terminology has a logical basis. Some have just evolved over the years. The same terms in photography mean a different thing, but in cinematography, you typically find these terms used in the following way:
|Contrast Ratio||Face||Difference between brightest and darkest portions of the face.|
|High Key Lighting||Scene||Difference between brightest and darkest portions of an entire scene is low, but the scene itself is bright and cheerful. Moody scenes aren’t counted.|
|Low Key Lighting||Scene||Difference between brightest and darkest portions of an entire scene is high|
I hope this has helped you understand contrast ratio, high key and low key lighting. Please let me know what you think in the comments below.