Understanding Lighting Ratios for Photography

Knowing how to light a subject is one of the most important skills for a photographer. It’s more than just a technical necessity; the manipulation of light and shadow directly impacts the mood and feeling of an image.

So, Jay P. Morgan has taken it upon himself to go over the basics behind lighting ratios. Regardless of your subject, these building blocks are essential to understand in order to step forward as an image maker:

In the studio, lighting ratios refer to the strength of the key and fill lights, and, by extension, the exposure difference between the highlights and shadows. Morgan goes over some simple setups and explains just how mathematical lighting ratios translate into imagery.

1:1 lighting ratio

As you can see, a 1:1 ratio signifies an evenly lit surface. Both sides of this model’s face are equally exposed, producing a flat light without much dimension.

2:1 lighting ratio

A 2:1 ratio has a bit more depth, with more pronounced highlights and shadows. However, it’s not a drastic departure from the 1:1 ratio, so you’re not losing much detail in the darkest areas of the shot. The highlighted side of the model’s face is about one stop above the shaded side.

4:1 lighting ratio

Because photographers work in divisions of two, the 4:1 ratio comes next, featuring a shadow side measuring about 2 stops below the highlighted side.

8:1 lighting ratio

You’ll start seeing drastic differences in your highlights and shadows around the 8:1 ratio. As you might have expected, this image features a three stop difference between the highlights and shadows. Theoretically, you could keep increasing your ratio, but in practice you’ll rarely want to go beyond a ratio of 8:1.

The easiest way to measure out ratios is with the aid of light meters. Morgan uses two Illuminati meters just outside of the camera’s frame – one facing the key light straight on, the other placed in the shadow cast by the key light hitting the subject. The stop difference between each meter’s exposure reading can then be used to calculate the lighting ratio.

Knowing how to take control of the highlights and shadows and what different ratios signify can be incredibly useful when it comes to pre-visualizing shots. Instead of hoping that you’ll stumble into a situation that will suit your purpose or mood, manipulate your surroundings to suit your needs.

“Understanding ratios and how you’re going to use them in the end, whether it’s all digital or not, whether you’re gonna make these into black and white or you’re gonna make them into color will allow you to make the correct decision on set that will give you the image that you want.”

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