Flash Color Correction: A Quick and Dirty Example

Above: a quick demo of the effect of color correction gels on a hotshoe flash.

You can put any sort of gel on the head of a hotshoe flash. Attach a blue gel, for example, and you can turn a white wall into a blue background. Easy.

The more refined skill to master, though, is using color correction gels.

The idea: put the right gel on your flash so that the light from your flash matches the ambient light in a location.

Shooting in someone's living room at night? You're probably seeing tungsten-balanced lights. Add a Full CTO (Color Temperature Orange) gel and the light from your flash will change from daylight-balanced (5500k) to tungsten-balanced / indoor (3200k). Or, maybe you need a bit less: a 1/2 CTO or just a 1/4 CTO.

Shooting in an office? Add a Full+Green and your flash will better match the greenish light the overhead fluorescents probably provide.

Shooting in open shade outside? The light is probably quite blue in color temperature ... so put a 1/2 CTB (Color Temperature Blue) on your flash.

Now, that's step one.

The quick example above is a reminder how the gels change the look of the light -- in a shot that is white-balanced for about 6000k. (That's not a magic number -- it is just a match for the light present for the first, ungelled shot.)

So, you've done step one: you've matched your flash to the color temperature of the ambient light.

What's step two? Change your white balance to match.

So, let's say you are in a living room at night: gel your flash (with CTO) and then set your White Balance to 3200k (or "indoor" or "tungsten).

Try it out.

Just Blue

In yesterday's post I mentioned using a Honl "Just Blue" gel to turn a white wall into a blue background ... so here's that gel. You buy a velcro strap (Honl sells a good one, or Opteka makes a cheaper but not-quite-as-good "clinch band") and put that around the head of your flash. Then you stick the gel -- which has those little velcro fasteners on it -- on the flash head, attached to the velcro band. Honl sells the gels in little kits, so you can get color correction gels, color effects gels, or a "sampler" with both.

Gelling Your Flash

Recently, I've had to use gels on my flash for both color correction and for effects.

It occurred to me that, if someone is interested in gelling their flash, they may easily be led astray by the "advice" they find on photo forums. You know, those same people who tell you to use the bottom of a 2-liter soda bottle instead of a Gary Fong diffuser. They're out there, in the forums, and telling everyone to ...

• buy big sheets of color gel material and velcro fasteners
• spend all day cutting the gel material into strips and carefully attaching the velcro
• somehow label the gels so you'll be able to figure out which one is the full "Color Temperature Orange" and which one is the 1/2 "Color Temperature Orange" during the pressure of a shoot, in the dark.

Great. Because you need to spend hours doing that to save about $20. Nothing like work that equals about $5 an hour and looks kinda shoddy at the end of the day. Let me save you the time, but cost you about $50. First, know what you want to do. The idea is this:

The Problem:
 Your flash puts out light that is pretty close to the color temperature of 5500k. So if you go into an office and want to use it to augment light coming from overhead fluorescent panels (which are kinda green if you shoot them with Daylight white balance instead of Fluorescent white balance), you may find a mismatch that can create color casts somewhere in the image. Or, if you go into someone's living room and want to add to the light coming from their table lamp (possibly balanced for 3200k) you will have to choose to set your white balance to match your flash or to match the lamp -- which can mean either a blue or yellow cast in some areas of the image.

The Solution:
Put a gel on your flash to match it to the existing light in the space. Then, you can set your white balance to match. In other words, in an office you would make your flash a bit green to match the greenish light fluorescents put out, and set your white balance to Fluorescent. In a living room, you would gel your flash to make its light close to 3200k color temperature, so it matches the living room lamp, and then set your white balance to "Indoor" or "Tungsten."

So what you need is the right gel -- and you can get custom made ones for relatively cheap, and quickly attach them to your flash. (And then, if you want to explore the world of "painting with light" or other color trickery, you can get additional gels to work with.)

Here's what I recommend:

1. Get a Honl Speed Strap.
This is just a strip that wraps on the head of your flash -- it's basically one size fits all for any hotshoe flash -- and that gels can be Velcroed to.




2. Get a set of Honl Color Correction Gels.
These come with a two of each of the important gels for making your flash match the conditions you'll find in the world. They attach quickly and easily to the strap, and take up almost no space in your camera bag. Adding flash to an office shot? No problem. Adding flash to a living room shot? No problem. Purposefully warming up a shot? No problem.




3. Later, get a set of Honl Color Effects Gels.
Then, you can spend hours in the dark, playing with light.




As an example, the image on this page was made with a "Bright Red" gel and a "Just Blue" -- I set my camera on a tripod, darkened the room, set my aperture to f/11 and the shutter speed to 8 seconds. I held my flash in my hand and then manually fired it in varying positions -- set on low power -- a few times with each gel.