Joshua Csehak,
Cinematographer

Diffusion Behind the Lens (and a Little in Front)

Posted by jcsehak on November 19, 2012

Armed by my success with using Tiffen’s Back Diffusion FX filter in front of the lens to reduce the C300′s green aliasing issue, and inspired by Shane Hurlbut’s post about diffusion behind the lens, I decided to see for myself what behind-the-lens-diffusion was all about. So I went to Walgreens and picked up the most transparent stockings I could find, and to my local fabric store and got half a yard of a bunch of different materials that I thought might be interesting: Tulle in white, navy blue, and brown (they were out of black, thanks to Halloween), a wider white net, a denser black stretchy net, black tulle with sparkles in it, and some black lace.

The stockings:

White tulle

Wide white net:

Black tulle with sparkles:

Black lace:

Black stretchy stuff:

What I learned:
-The pantyhose does indeed look gorgeous!
-The pantyhose has a very diffused quality to it, but if you want less of an effect, tulle and net work wonders.
-The white net is sufficient to diffuse the lamp enough to completely knock out the green fringing issue, and give the frame a more organic look.
-White, however, even in the wide net, has an effect almost like fogging the film. The blue tulle holds the blacks better than the white net. I would use black only, unless you want to make it milky for some reason.
-Be careful when stopping down with the wide net, or even tulle — the net can actually start to come into focus. This is much more noticeable when moving the camera.
-While the brightness of the fabric makes a definite difference, the color doesn’t seem to matter at all. However, I didn’t try something like a bright red, that might be interesting to see.
-The black stretchy stuff is too dense, and not usable at all

I also tried it with the fabric in front of the lens. On the whole, the diffusion was much more prominent and kinda cheezy looking. Behind the lens FTW.

Has anyone else had interesting experiences with it? Let me know in the comments!

Josh out.

4 Responses to “Diffusion Behind the Lens (and a Little in Front)”

  1. Josh – Great job putting what you read into action!

    • jcsehak said

      Thanks Shane! I’m indebted to you for posting the technique in the first place! It’s a really useful tool to have in my arsenal.

  2. Brina said

    Josh:
    I learned many years ago to ALWAYS carry a black ladies knee-high in my gadget bag. It’s great for diffusion and can work in a pinch for an ND.

    Also, you can get a simple effect by using dry-erase markers on cellophane. Just paint different colors in whatever area you want the diffusion in and place in front of the lens.

    @loh@, Bree

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