User Tools

Site Tools


omd:wb

managing white balance on the Olympus cameras

introduction

  • 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:

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

via the WB settings

  • 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
omd/wb.txt · Last modified: 2014/10/14 10:24 by gary1