A couple of years ago, I was shooting my daughter holding our infant son. I used a fill flash to the side, but had a horrid greenish hue to the picture. Someone wisely pointed out that I was probably shooting in a room with fluorescent lights. They were right.
So what do you do to overcome that.
1- You can use a light modifier (they call them gels)
2- You can turn off the indoor offending lights and use your own lights (flashes)
3- You can ramp up your own light (flash, strobes) to overcome the ambient light that is causing the hue chaos.
There is much talk of this mixed lighting... check out the strobist's blog on using gels to correct for this color.
Anyway, I took a shot today with just our indoor lighting on one side and the morning light from the window left of subject. Here's what you get. (And I corrected for the indoor lighting)
Not that we always have to have perfectly uniform lighting... We just have to be aware of what hue each light will bring to our image. So simply stated, greenish = fluorescent, bluish = tungsten. Play around with the white balance on your camera or in your photo editing software afterwards. And then you can take it to the next level with gels (more to come).
This image I will use as pick of the day... even though it is really just an example of my next blog.