unlike film cameras, digital cameras can alter the colour balances to deal with different coloured light sources
this is called the “white balance” setting
light sources have a "colour temperature" which is measured in degrees Kelvin, for example:
blue sky (ie. shade outdoors on a sunny day) = 8000K
cloudy day = 6000K
flash = 5500K
midday sun = 5300K
early morning or late afternoon sun = 4500K
sun 1hr after dawn or 1hr before sunset = 3500K
tungsten light = 3000-3300K
sunrise or sunset = 2000K
whilst your WB settings do not directly affect your RAW files, they do affect the way the camera's light metering assesses the scene which could create erroneous exposures
Olympus cameras also have other settings that affect WB:
Menu:Cogs G:All WB+/-
this allows you to fine tune your camera preset WB settings on the Amber and Green axes
Menu:Cogs G:WB Auto Keep Warm Color
in AutoWB, it provides a warmer WB if set to ON, although it tends to be too warm in tungsten lighting
Menu:Cogs G:flash+WB
allows you to tell the camera to automatically use a specific WB setting when a compliant flash is used
this is ignored if just using PC sync or central pin to fire a flash
when using gels on your flash and creating a custom WB, when using a compliant flash the Menu:Cogs G:flash+WB item MUST be set to OFF otherwise the custom WB will NOT be used!!!
allocating a WB setting on Olympus cameras
you must be in a PASM mode or Movie mode (iAUTO, SCENE modes and some ART Filters will disable WB changes)
you must not be using Color Creator mode as this will disable WB changes
then you need to access the WB settings either via:
press the down arrow button on rear of camera if this has been allocated to WB
go to Menu, Cogs G, WB
autoWB
in order for the camera to determine the autoWB measurement, there needs to be neutral or near-neutral tones in the scene that are within the exposure range (ie. not blown out from severe over-exposure or blocked out from underexposure).
the camera then rapidly determines the best WB setting to make these as neutral as possible
when NOT to use autoWB
when you want consistent WB between exposures
panoramic stitching
HDR
photoshoots where you want to simplify your workflow in post-processing
when there are no truly neutral tones in the scene and colour accuracy is important:
artworks
portraits
when you want the light source to give colour to your image
warmth of sunsets or candle-lit subjects
creative colour effects such as using gels on flash in daylight
factory preset WB settings
sunny = 5300K
shade = 7500K
cloudy = 6000K
incandescent = 3000K
flourescent = 4000K
underwater
flash = 5500K
CWB setting
the CWB setting allows you to dial in a colour temperature in degrees K
how to perform a custom WB
you need a white piece of paper (or preferably a true neutral target) which is lit by your light source without reflective glare bouncing towards the camera
neutral targets have LAB color space variables of a (red-green axis) and b (yellow-blue axis) equal to zero and include WhiBAL cards
if you use normal white paper, it is actually a little blue due to optical enhancement agents which convert UV light into blue light to make it brighter, so your custom WB will render the scene a touch warm
set your exposure to ensure the paper is not blown out or severely under-exposed
perform a autofocus lock or use manual focus to avoid the next steps struggling as it can't lock AF on a plain sheet of paper
if you get error message NG Retry with the following, it means that either:
your target was severely over-exposed, or,
your target was severely under-exposed, or,
your target was not suitable as a WB target (eg. no near-neutral tones)
if using a flash, ensure Menu:Cogs G:flash+WB = OFF otherwise the custom WB will not be used (unless using a non-compliant flash)
cameras with One Touch WB assigned to a button
press and hold the One Touch WB button then aim camera at your target then press the shutter
you will then have the option of assigning it to custom balance 1 or 2
scroll across to either custom WB 1 or 2, then press the INFO button
aim camera at your target
press the shutter button
you cannot use the Menu:Cogs:G:WB to set a custom WB although you can use this to allocate your WB to a pre-set custom WB, or you can modify a pre-set custom WB on the Amber and Green axes and preview the result using the REC button
fixing WB issues in post-processing
most RAW connversion programs (eg. Adobe Lightroom) and jpeg editing software tools, allow you to change the WB setting
this can be changed to a preset value (eg. As Shot, Daylight, etc)
alternatively you can use the eye dropper to select a neutral tone in the image and the software will determine the best WB for that tone
it is handy if you have taken a shot with a neutral WB target in the scene, and then the WB setting for that image can be used on other images taken in the same lighting