How clean are your whites?

Cambridge in Colour finally comes into the frame with a top hit on Google!

I was looking up "white balance". Hopefully we can avoid problems caused by auto white balance because we'll be using manual balancing techniques but what's that about?

According to Cambridge in Colour;

White balance (WB) is the process of removing unrealistic color casts, so that objects which appear white in person are rendered white in your photo. Proper camera white balance has to take into account the "color temperature" of a light source, which refers to the relative warmth or coolness of white light. Our eyes are very good at judging what is white under different light sources

It's a peculiar process because my eyes (and brain) adjust to different colours of ambient light without making any fuss with my conscious thought. It just happens. Stick me in candlelight or moonlight, my brain is going to interpret "white" as the lightest colour and all other colours will be relative to that. It's automatic.

The "unrealistic colour casts" may, in fact, be entirely realistic but the camera doesn't have our eye and brain. When we view those images, we are back to the eye/brain combo though. Food for thought.

Skipping over the technicalities of "blackbody" temperatures we find a chart describing the relative "temperatures" of different light sources.

Image source: www.cambridgeincolour.com/

As far as I can make out, this takes us from a relatively red light at low values to a bluer hue at higher values? A balanced "white" light lies in the 5000K to 6000K region.

....aaaaanddd this means what exactly?

I guess this is a matter of consistency across a number of shots. A deliberate shift in white balance might be desirable where a change of mood or time-shift is being portrayed. Where consistency is the requirement and ambient colour temperature changes, white balance is what we need to consider.

Image source: www.pitt-pladdy.com/blog/

Having used Photoshop-like programmes for a long while, I'm intrigued to find out the pros and cons of post-colour grading versus the use of a neutral reference. It would appear that in anything other than a "colour-critical" project, the comparative colour temperature will be as effective as the absolute.

The main thing we need to worry about for general photography is white balance. White balance is simply a matter of adjusting the levels of RGB to ensure that white objects appear white in the photo. For example, when things are lit by tungsten, we need more blue and less red, else the photo would come out looking very yellow/orange. So for the examples above, we can compensate and get reasonably good colour back:

Source: www.pitt-pladdy.com/blog/

Image source: www.pitt-pladdy.com/blog/

Of course, "colour critical" could apply to anything which involves more than one shot, taking place across any period of time and possibly by a team of more than one person.... which just about covers it.

Best to learn it properly and then try an informed comment?

Very probably.