Diffusion is an important part of getting the light in a scene to look pleasing. While there are plenty of professional materials made just to diffuse entertainment lighting (like silks, spun, frost, etc.), sometimes you run out, don't have what you need with you, or just want a different quality of light that you can't get with what you currently have. That's where regular household diffusers come in. Cinematographer Domenic Barbero did a test with Casey Schmidt of Northwest Grip to see what kind of light would be produced by using everyday items as their diffusion material.
Here's what they did for the test:
So Casey Schmidt of Northwest Grip and I conducted a little test recently on diffusion. Sometimes on low budget shoots, people remember to bring lights, but often forget the modifiers. So what do you do when you need a little diffusion? Well, you start looking around your house or around set for some common items. Here's the results, read below to know more about the test.
Garbage bag 1, garbage bag 2, hand towel, visqueen, paper towels, computer paper, t shirt, dress shirt, pillow case, bed sheet, and opaque tupperware.
Our key light was an Arri 650 tungsten fresnel on full flood. f9.6
Our fill light was a Desisti Magis 300 tungsten fresnel. f4.0 (never adjusted exposure when key was under f4.0)
Our kicker was an Arri 150 tungsten fresnel with a small amount of diffusion on it. f4.0 (never adjusted exposure when key was under f4.0)
Camera was RED Epic set to ISO 320 and balanced at 3200k. Red Color 3/Red Gamma 3 and 5:1 compression. This is ungraded minus RC3/RG3 specs.
And a picture of one of the setups -- this one used a white T-shirt:
The first thing to note is that materials that aren't made to withstand the immense heat produced by Tungsten heads need to be kept a safe distance away, or there is a chance they can burn (though even materials made for hot lights can also burn). That's part of the reason in the photo above the T-shirt is kept a safe distance away attached to the frame. Equivalent or less wattage HMIs, LEDs, and Kinos don't produce as much heat, so you can use a wider variety of materials for diffusion closer to the source -- though generally the farther the material is from the light source, the softer the light falling on the subject will be.
For example, since most LEDs produce almost no heat compared to their light output, you can use easily flammable materials like paper right in front of the source. I've done this in a pinch more times than I'd like to admit, but the reality is, any diffusion is good diffusion. Bed sheets and other large, cheap materials are more common than you might think, because they work great when you're on a budget or you need more or larger diffusion than what you have with you. Either way, whatever works, works, because nobody sees what the lights look like when they're watching something, they just see the final result.