NOTE: This was a light gray background that I hit with a blue gel to make the background look blue
The first time I saw someone use a gel on a light was while watching a crew film a Hollywood movie.
I waited for a lull in the action and timidly asked one of the lighting guys what he was doing. He explained he was using a “Rosco CTO” and moved on.
Ok – well that was helpful…
I did some research and learned enough to figure out what he was talking about and the rest is history. Here’s some very basic info on using gels with your photo flash.
Gels are thin strips of colored plastic that you place over your flash/strobe/light to change the color of light coming from the source. You can do this to balance two different light sources, i.e., if you’re shooting in a tungsten lighting situation but you want to correct your daylight balanced flash. You can also do this for creative purposes, or what some people call “color key shifting.”
I most often use a CTO (color temp orange) gel or a “Window” green gel. The CTO is used to balance tungsten light and the Window green is used to balance florescent light.
On the creative side, you can use almost any color gel on a background light (studio strobe, flash, etc.) to change the color of the background. Buy some white or gray seamless paper – light it with a strobe featuring a red gel – you have a red background. Pretty cool.
You can get a Rosco Color Correction Kit with 16 filters (you’ll have to cut them down to size to fit your flash). These work very well but aren’t as convenient as some pre-made solutions. If you use the HonL stuff like I do, there is a great kit Honlphoto Gel Kit 2 for about $30.
You can also sometimes get free gel sample packs from lighting, grip and camera stores, although this is getting tougher and tougher to do. These sample gels are often large enough to cover most flashes so in the event you can find one, you can start practicing with gels for free.
The best thing to do with gels is practice with them. Try lots of different scenarios. If you have two or more flashes — that can help you get very creative with light because you can use different gels on each flash and use one on the background and one on the subject. Give it a try.