Diffusion yet again

I just can’t stop…

In my last post I mentioned that adding diffusion at the same size as the light source will not soften the light (change the shadow edge transition), but will change the contrast. Adding an additional layer (or more) will still maintain the same light quality, but spread it out a little bit more and also lose a lot of power.

That got me to wondering just how much light is bouncing around the room to add to lower the contrast and fill in those shadows. Obviously in a very large studio with black floor, walls, and ceilings there will be nothing to bounce off of. Similarly if working out doors in an open field there will be no extra fill. But I am working in a modestly sized room with an 8-foot white ceiling, a light natural wood floor, and white walls.

Time for another test!

 The Interfit Deep Zoom Reflector

The Interfit Deep Zoom Reflector

Here are three images made with the Interfit Deep Zoom reflector. The first image is with the “bare” reflector. Next is with the included diffusion “sock” and the third image has a sheet of diffusion material added to the front of the modifier for “double-diffusion.” I kept the camera settings at ISO 100, SS 1/160 sec., and F/9 so that the ambient light effect on the image would remain the same. I raised the power of the flash in each image to compensate for the diffusers and to maintain the same flash exposure.

Click to enlarge

Here you can see that the shadow edge changes slightly from bare reflector to diffused reflector as the light is homogenized from multiple sources (flash tube, glass dome, reflector) all contributing their own shadows to one source (the diffusion material). And you can see that the shadows open up a little bit and the background gets a little bit brighter. Comparing the second image (single diffuser) to the third (double-diffuser) note that the shadow edge that determines the light quality is exactly the same. The diffusion is the same size as the light. If the light size doesn’t change the quality of light doesn’t change. What changes here is how much power you need from your lights to compensate for the light loss from the multiple diffusers. Again, don’t confuse contrast with quality (hard or soft) of light.

Now go out and light up your world!

John