Balancing Flash with Fluorescents

  The classic, and most common, solution is to attach a “window green” (or “plus green”) gel to your flash head.
When the ambient light in a room is green (from fluorescent) and you’re using a green gel on your flash, with the fluorescent light (FL) balance selected on your camera, you will achieve balanced lighting, or all white. White balance, at FL, adjusts the value by 33 units of magenta, which is what is needed to cancel the green effect.

   In the real world, however, the problem is a bit more subtle and challenging for two very good reasons. First, fluorescent lighting technology has advanced, so instead of the standard value of 30 color correction (CC) units of green light, today’s fluorescent lights are available in a wide range of light temperatures. In fact, some fluorescents have a light temperature warmer than tungsten. (Generally, tungsten light is approximately 2,700–3,300 on the Kelvin color temperature scale, while traditional fluorescents are more than 5,000 K.)
The second challenge to balancing your flash with fluorescent lights is that many interior spaces have a mixture of daylight, incandescent and fluorescent light.

  When you find yourself in a room that is predominately lit with fluorescent light, your first step toward an accurate balance is to test the light to determine where it is in the broad fluorescent range. Shoot a few images with just the ambient fluorescent light. If they tend towards green, then use the standard green gel. If they appear to be more orange, then the fluorescent light is closer to tungsten, or incandescent. In that case, use a “CTO” gel, which typically balances a flash with incandescent light.

 In neither case will you find an exact balance because there are so many varieties of color temperatures from fluorescent tubes that your images will either show a little green at one end of the scale or a bit of orange at the tungsten end. Unfortunately, cameras don’t come with a white balance FL setting for every minor difference in color temperature value in today’s fluorescent tubes.

The small difference between your flash and any of the various fluorescent values under which you might find yourself shooting usually only affect the fringes of an image where the light from the flash is diminished. Your subject, which receives most of the flash’s illumination, will typically look very much in balance.

 _ JBStran.com