Colored gels are commonly used to balance flash color temperature with the color temperature of ambient light. But you can also use gels to add creative color effects to your photos.
I recently shot this portrait of my son to commemorate his Shichi Go San (7-5-3) ceremony. Shichi Go San is a Japanese rite of passage performed at ages 3 and 7 for girls, and at age 5 for boys.
The background is a black piece of cloth, stretched across a Manfrotto background stand. To separate him from the background, and add visual interest, I used a single flash with a DIY blue gel to add some color to the background. In this article I’ll explain how to make your own gels, and how to use them. Lighting your background separately from your subject, with or without gels, is a great way to add depth to your photos and can help separate subjects from a dark background.
Here’s how it looks with only the background light:
First, an overview of the lighting setup for this shot:
Main Lights: 2 x Canon 430EX II Speedlites at full power, fired through 24″ Lastolite EZY-Box softboxes at camera left and right, just outside the frame.
Background Light: Single Canon 430EX II Speedlite in a snoot, with DIY blue gel, fired at the background from the right side of the set. I aimed this flash so that the hotspot would be centered behind my son’s head.
Exposure: 1/200, f/6.3, ISO 200
Lens: Canon EF 50mm f/1.2L
Camera: Canon EOS 5D Mark III
How to make your own DIY Gels
Any piece of thin colored plastic will work well. For the above photo I used two circles of plastic that I cut from a notebook cover. I purchased the notebook for 100 yen, or about USD $1.25. Experiment with different colors to find what works with your creative style, and for the particular photo you’re creating. For portrait work, I’m partial to cool tones, especially blues. Warm colors appear to pop out against cool colors, so a cool colored background works well to compliment skin tones.
In addition to the gel, you also need a snoot. A snoot narrows the light, and gives a spotlight effect. This keeps blue light from spilling all over the place. For this photo, I used a Gary Fong Powersnoot, because I already have one. But a piece of black poster board folded into a cylinder works just as well.
My 8-year-old daughter taped the blue plastic to the end of the snoot for me. If you don’t have an 8-year-old, see if you can borrow one from a friend or relative. Failing that, you can also tape the plastic onto the snoot yourself.
How much flash output?
So, how much flash do you need on the background to get a nice color effect? At first glance this may seem counterintuitive, but here’s the rule:
More flash = lighter color
Less flash = darker color
The reason for this is simple. The brighter your background flash, higher the luminosity of the color hitting the background will be.
So for a nice, deep blue like in this photo, you only need a little kiss of light from your flash. I powered a single 430EX II at 1/4 power for the background light, compared to two 430EX II’s at full power for the main lights. My background flash was about the same distance from the background as my main flashes were from the subject, so basically the light on the background is 4 stops weaker than the light on the subject. (1 flash @ 1/4 power on the background, 2 flashes @ full power on the subject.)
I hope this article has given you some ideas about how to make your own DIY flash gels from inexpensive materials, as well as how to use gels to add creative color effects to your photos. I’d love to hear from you, feel free to comment below or reach out to me on Google+ or Facebook.