Greetings! Last week I brought up the subject on the qualities of light and in the last question, I made you wait until today for the answer. Here you go.
How do the clouds alter the quality of the light?
Diffusion. The light rays from the sun travel relatively parallel creating a highly directional beam of light. When the sunlight enters the clouds, the light rays pass through the cloud molecules scattering the light in various directions. The resulting sunlight is transformed into a mile wide source that was once, perspectively, a 3 inch spot in the sky.
Fog, smoke , and haze are other types of natural diffusers that will scatter the light and work great within the image frame too, they can add an interesting mood or effect to a photograph. The only problem is these beauties are almost impossible to control.
A soft box uses a diffusion material to soften the light
So, when you want a diffuser you can control, any kind of transparent or translucent material will work. Fabric, like silk, linen, nylon, and muslin are great. You can also use glass, plastics, your bed sheet, or even your shower curtain. If you want professional gear, manufacturers like Rosco or Lee make dozens of grades of diffusion gels and you can get it by the sheet or the roll at your favorite photo store or website.
The size of your diffused light depends on how much light is illuminating your diffusion material and the size of the material itself. If you have a light that is 6 inches in diameter and it ‘fills up’ 20 inches of material with light, you now have a 20 inch light source. Pretty simple, right? Keep in mind, If you are using a large piece of diffusion, you may need multiple lights to illuminate all of the material.
The quality of the light depends on the thickness and density of the material. The denser the material, the softer the light will become. Also, the light will appear to be dimmer because the light’s intensity is spread more evenly across the diffusion material instead of being a concentrated spot.
Warning! Be aware to keep the shower curtains and sheets far enough away from those HOT lights or you’ll end up with a very large orange light source. The professional quality diffusion gels are made to be heat resistant, but NOT proof. Just use your brain on that stuff.
A diffusion gel attached to the barn doors of a light with a commonly used clothespin (aka C47's).
My final comment, no matter how stupid it looks, don’t be afraid to use any kind of diffusion you can get your hands on to get that perfect effect that you want from the light. I’ve even used food storage containers…empty of course.
That’s it for today, thank you for reading and join me on every Techie Tuesday. Please leave any comments or questions.
Peter
Peter Pechacek is a photographer and filmmaker in Orlando, Florida. He contributes weekly on Techie Tuesday.
