Understanding Lighting/Contrast Ratios in Photography

Understanding Lighting/Contrast Ratios in Photography

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The best part about photography is that you can use your imagination, add your creative ideas and create the final image. But do you know what comes between this imagination and the final image? Many technical aspects with which numbers are associated like aperture, shutter speed and ISO. But don’t you feel that photography is beyond these numbers. We like a particular image because of ambience, mood; its certainly not because it was clicked at f/8 or f/2.8. These are mere numbers and do affect the image but most of time photographers get stuck between these numbers and eventually lose the plot. 

Remember you enter the studio hoping to create that evocative portrait. And while setting lights you get entangled in numbers because you have to create mood using 2-3 lights. You may eventually shoot a picture but it will be devoid of the soul you wanted to instill. Ever thought why does it happen? Its because of our limited understanding of something called Lighting Ratios. 

Most people know this word but have been intimidated by it to an extent that they do not even attempt to learn. 

In this video Jassi Oberai has simplified the entire process of Lighting Ratios. 

Lighting Ratios are also called Contrast Ratios. You need a light meter to understand these ratios. In the above video Jassi is using Sekonic L-308X LightMeter to demonstrate the same.

So what exactly is Contrast Raio or Lighting Ratio as some call it? To simplify it is the difference of stops between two lights say e.g Key Light and Fill Light.

Key light is the most powerful light in your set-up. When used it creates shadows. You use fill light to fill those shadows created by key light. Needless to say that the intensity of fill light is either equal to or lower than key light. In other words, the difference between the intensity of Key Light and Fill Light is called Contrast Ratio. 

But why is it even important? Using this light/contrast ratio, you can ensure what kind of mood you want to bring out – dark moody or bright happy or sombre somewhere in between. To understand lighting ratio you must know two aspects: one the stop difference and second how does this stop difference impact lighting ratio. Pls refer to the chart below:

C:\Users\Optimus Prime\Desktop\Image 1.png

Referring to above chart, 0 stop difference means that the light intensity difference between Key and Fill light is 0, in other words they are equally bright and so on.

If you are still confused refer to this calculation:

C:\Users\Optimus Prime\Desktop\Image 2.png

I hope it will be clear now.

How to Calculate Lighting Ratio?

You need a light meter to calculate lighting/contrast ratio. You may argue that why need a light meter when we can instantly refer to the histogram. Well histogram is just an indicator of whether you are able to achieve correct exposure or not but it does not talk about the lighting ratios. For that Light Meter is a must. In the above video Jassi has used Sekonic Light Meter – Sekonic L-308X which is the entry level light meter from Sekonic.

Setting it up

The first light to set up is Key Light because that is the most intense light in your set-up. Next light to be set up is fill light. For 1:1 ratio, intensity of both key and fill light have to be exactly same. Here are the examples of images:

C:\Users\Optimus Prime\Desktop\Image 3.png

Lighting Ratio= 1:1

Lumix S1, f/11, 1/125, ISO

C:\Users\Optimus Prime\Desktop\Image 4.png 

Lighting Ratio= 4:1

Lumix S1, f/11, 1/125, ISO


C:\Users\Optimus Prime\Desktop\Image 5.png

Lighting Ratio= 8:1

Lumix S1, f/11, 1/125, ISO

Now check the images where 3 lights are being used – Key light, fill light and hair light. In this set-up, Ratio between Key light and fill light is 8:1 and that between Key Light and Hair Light is 2:1

C:\Users\Optimus Prime\Desktop\Image 6.png 

Lighting Ratio (Key and Fill light) = 8:1

Lighting Ratio (Key and Hair light) = 2:1

Lumix S1, f/11, 1/125, ISO

Concluding Lines

Some may say that they can achieve this without the use of light meter. Well, there is a difference between trial and error and being accurate. And with trial and error also, you are never certain about exact ratios getting achieved. Light Meter is extremely important gadget and Lighting Ratios is very important aspect of studio lighting set-up to create exact mood in the image.


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