Go warm or cool with colour correction gels

1 Orange and blue

These colour correction gels are Colour Temperature Orange (CTO) and Colour Temperature Blue (CTB). They come in different strengths, such as 1/2, 1/4, 1/8 and full (and you can double up the gels to make them stronger). A full CTO will shift your light temperature from daylight to 3200 K, and a full CTB will shift 3200 K to daylight.

2 Daylight-balanced

Here are the effects of the flash without any colour gels. Speedlights are daylight balanced, so they’re roughly the same light colour as the daylight at around 6000-6500 Kelvin. By setting our white balance to this, the subject’s skin tones look natural, but the backdrop looks dull.

3 Fit a CTB gel

We used a pack of Selens gels, designed to fit neatly over a Speedlight with a rubber band. First we used a 1/2 Colour Temperature Blue gel. This has the effect of cooling the light source. To compensate we can shift our white balance to around 9000 K, which cancels out the blue light.

4 Warm the ambient

Once our white balance is locked in, any other light sources in the scene that are higher in Kelvin will appear cooler, while any light sources that are lower in Kelvin will appear warmer. As such, the shift in white balance has a profound effect on the warmth of the backdrop.

5 Fit a CTO gel

As well as warming the backdrop, we can also go the opposite way and cool it down by using a CTO gel instead. We used a full CTO here. Keep in mind that whenever you fit a colour gel, you’re going to be reducing the strength of the light, so you’ll need to compensate by increasing the power by a stop or so.

6 Cool the background

The CTO gel warms the skin tones, so after compensating for this by reducing the white balance to 4000 K, the rest of the scene becomes very blue. Note, too, how the shadow side of the face here is tinted warmer than the highlight side. This is the ambient light mixing with the flash.