Just like your laundry — keep your whites white!
White balance is colour temperature, measured in degrees Kelvin (K). In its simplest explanation, white balance is an adjustment to ensure that the colour in your photos are accurate to how they appear in real life. It is the removal of unrealistic colour casts in the image.
If an object appears white in real life, but has a blue or yellow tint in your photo, the white balance needs to be adjusted in order to render the white as white in the photo — which then also calibrates the colour of the entire photo.
To achieve the correct white balance, one has to take into account the colour temperature of the light source illuminating the scene, i.e. – the warmth or coolness of the light illuminating the scene.
What this means for wide field astrophotography is that shoot location and sky conditions will dictate the white balance selection in your images, which it’s why it’s important to know how to manually set the white balance.
Cameras come with various WB presets, which are fine to use, but only when you’re shooting raw.
Thankfully, the white balance can easily be changed in post production if you shot raw.
If you’re only shooting to JPEG instead (which we don’t recommend for astrophotography), it’s essential that you select the correct white balance while shooting.
White balance for night photography
Daylight (~5200K) is nearly always too warm for night sky photos. Generally cooler settings of between 3200-4800 are used for astro photos, depending on your location and environment.
In light polluted skies, the excess ambient light reflecting off the atmosphere creates a warm glow to the sky, therefore in urban areas a lower (colder) setting around 3,400-3,900K would be more suitable. In darker skies, settings of 4,000+ will yield better results.
To find the best WB for your photo, start with the suggestions above and shoot test photos in increments of 100, adjusting either cooler or warmer depending on your location and the desired look of the image.
Remember, always photograph in RAW!
We’ve compiled some examples of what you can expect in dark skies vs. urban light-polluted skies. Choose wisely!
White balance setting examples, shot in darker skies
Urban light-polluted night-sky photography white balance examples
While cool is cool and warm is warm, the difference that artificial light makes in the final image in regards to colour temperature is quite different to what it looks like in darker locations away from the city lights.