My Roscoe gels came in this week and I'd yet to actually play with them. I set up two strobes for this, one with a red gel (#124 Red Cyc Silk) filling the background (a while posterboard) and a green gel (#122 Green Diffusion) camera lower left, illuminating most of the front of the gargoyle. With just the red flash, the background is entirely red (and a pretty menacing effect). With the green illuminating the gargoyle and spilling over onto the posterboard, it would cancel out the red wherever they met. This would leave a red background only in the shadows. A wider angle would reveal a relatively well-lit gargoyle with a red shadow.
I was originally attempting to shoot through the viewfinder of my Yashicamat so I switched to my 100mm macro to get closer in. When I abandoned that idea (I need a lot more light for that) I left the 100mm on when shooting the subject directly, resulting in a much tighter shot.
I also wanted to play around a bit with localized edits in LR2, so I punched the green to bring it out a lot more. I put a bit of a post crop vignette in, used a camera standard profile (new to LR2), and added some sharpening.
I left the strobes where they are, I might put the 17-55 back on and get a wider shot to show the red shadow. Actually, I might be able to put my whibal card in and remove the green entirely. Hmm, gonna give that one a try.
Anyway, tonight is a learning night. I've been wanting to play with color gels for a long time and now I have the ability to do so...
(Update, here's a wider shot)