During Brittney's studio headshot session, we did a little experimenting with creating backgrounds on a plain white wall.
Since our lighting setup of a tabletopped softbox and the two gridded strip softboxes kept most of the light from hitting the back wall of the studio, the white wall was now a dark gray.
That meant that we could then take another flash and light the background in a different way from how we lit Brittney. David Hobby of Strobist.com refers to this as "lighting on planes".
In the film/video world when you want to put a pattern on a background wall, you would use what is called a "cookie" - a metal disc with a design cut out of it. This is put in front of a focusable light that projects the design onto the wall, creating a pattern.
We were all out of cookies that day so to improvise, we used a Nikon SB26 with a set of barn doors to control the spill of light. We set it up facing the back wall and tried putting different things in front of it to try and create an interesting pattern. Tried a lot of things - garment bags, lace material, plastic cups, plants, nothing really seemed to click.
Until we found the remains of a skeleton lying around the studio.
Don't laugh, it actually worked out pretty well. Skeletons should be a part of any well-equipped studio. ;-)
We suspended the skeleton from a light stand and aimed the flash through the ribcage. We then just played around with the positioning of the flash and the skeleton until we got an interesting pattern on the background behind the model.
If we wanted to, we could also have added color to the background pattern by putting a colored gel over the flash. Now that I think about it, we also could have tried putting larger sheets of gels onto the skeleton itself, maybe in multiple colors and see if that would have produced a multi-colored background when the flash fired through it. Something to experiment with on a future shoot.
So the next time you're on a photoshoot and all you have is a blank wall behind your subject, try putting objects in front of your background light and see what happens. You never know when you'll end up with something cool.