Shooting outside the studio comes with a lot more variables you will have to contend with when lighting your shot. A common situation is having multiple light sources that don’t exactly match in color temperature. This could be cool daylight from a window and warm tungsten practicals inside or it could be that two lights you are using have a slightly different native colour temp and you want them to more closely match.
What is mixed lighting?
Mixed Lighting is a lighting
situation where more than one type of light is present. It can be intentional,
or a problem that needs to be solved either on location or when post-processing.
An example of intentional use of mixed lighting is the use of strobe and
continuous lighting together in a studio setting for special effects. This
combines a long enough exposure to show motion with the frozen image provided
by flash. An example of undesirable mixed lighting is the use of tungsten light
in a room with daylight coming through a window. No matter what white balance
you choose on your camera because the two light sources are a different color
your resulting image will have parts that are either blue cool or orange-red warm.
Photographically speaking, mixed lighting refers largely to the
color of two different light sources, more so than any other aspect of
differing sources of light such as flash versus natural light, or bright versus
dim, etc. even though technically, any two different light sources could be
Daytime ambient sunlight, for example, is roughly 5500 Kelvin
white balance temperature. Indoor lighting that is roughly similar to the
traditional Tungsten color temperature, on the other hand, will be in the
vicinity of 3000 Kelvin white balance.
If you want to learn how to work with mixed color
temperature lighting, here are some expert quick set of tips and techniques
that will help.
When shooting in mixed light, if you match your white balance to
one of the light sources, that light source will appear neutral in colour while
the other light sources show their true (relative) colour. For example,
shooting an indoor + outdoor scene with daylight white balance set would render
the outdoors "normal", while the indoors would be rendered with
whatever warm colour is coming from the lamps indoors. Oppositely, if you set
your white balance to an indoor setting, (incandescent, tungsten) then that
light would appear more neutral, while the outdoor light would appear extremely
If the difference between two light sources is great enough,
(dusk light is far bluer than normal daylight, for example), therefore
splitting the difference between the two light colours would result in both
very warm colours indoors and very cool colours outdoors.
When processing a raw photo that is captured in mixed lighting,
the same constraints apply when setting your overall white balance. If you
match one light source, the other will exhibit its relative colour. To fully
correct this and match light colours, localized brushes and/or selective colour
adjustments would need to be used, to cool down or warm up any undesirable colours.
Alternatively, if a special effect is desired, pushing the white
balance further in one direction can result in a very dramatic colourization.
Probably the most common issue is having windows and
doors in the background. Usually, this goes beyond the dynamic range of modern
digital cinema cameras and the best way to solve this issue is to use another
light on your subject to balance the exposure. Now, if you use a tungsten light
you’ll notice that it looks very warm compared to the natural daylight. It’s
very noticeable and can make things look unnatural.
To correct changes where you just want to do a
simple conversion from tungsten (~3200K) to daylight (~5600K) you can use a
gel. A CTB (colour temperature blue) gel is designed to do just that. The only
thing to consider with gels is that you will lose some brightness with gels as
they absorb light to make the color shift happen.
A modern alternative is to pick up a naturally daylight-balanced fixture for these scenarios. Or, better yet, get an LED with an adjustable colour temperature. Variable colour lights will be able to be balanced in most situations as you can tune them to the exact shoot.
Honestly, if you are looking to purchase lights
today you should just go with some LEDs. I’m not so convinced you need anything
more than daylight-balanced LEDs to start (brighter and more colour accurate
than variable colour temperature LEDs), but the new full colour LEDs offer a
much wider range of creativity.