What is white balance and what's the correct way to use it?

[mirekti]

In camera metering is generally about the luminance (brightness) of light, more usually that reflected from the subject, white balance is more about the colour of the source light.

Both systems cans be easily confused, metering by light or dark subjects, by lights behind the subject etc, white balance can be confused by the colour of the subject.

Despite the 'it's subjective' crew this is why I think its impoetant to understand how the camera is working, and where it can get things wrong, as this helps you get things right.

I'm sorry, but I believe you didn't understand my question. My point is to understand the way camera works and that's why I asked the question:
Is white balance metering related to light metering or not?
So let's say that before I recompose my image, the frame is filled with some light color (e.g. 2600K) that doesn't appear in the frame once I do the recomposition (e.g. 3000K), but I locked the metering at the first frame. Will AWB change to 3000K or it will remain at 2600K even though the metering is locked? 

[paul13walnut5]

I'm sorry, but I believe you didn't understand my question. My point is to understand the way camera works and that's why I asked the question:
Is white balance metering related to light metering or not?
So let's say that before I recompose my image, the frame is filled with some light color (e.g. 2600K) that doesn't appear in the frame once I do the recomposition (e.g. 3000K), but I locked the metering at the first frame. Will AWB change to 3000K or it will remain at 2600K even though the metering is locked?

AWB is an adaptive system, I don't know how rapidly it adapts,  or how accurately, ehich is why I tend to avoid using it.

[paul13walnut5]

@hjulenissen

I'm never going to win this one, and life's just too short.

If you are happy with your results then I'm happy for you.

You got your way, I've got mine.

I think it's important to understand at least a little about whats happening, and that was I believe the spirit of the OP's question.

Anyway, cheers.

[paul13walnut5]

@TrumpetPower

Good stuff, in defense of the humble bit of 'white' paper, its something that fits in the kit bag quite easily, and is less imperfect than awb etc.  paper will at least get you close enough that fixes in post are minor.

I'll try the styrofoam cup sometime.

I have the qpcards & a calumet grey white black card in my kit bag, but accept that even this is s bit cumbersome for many, especially given canons old fashion manusl wbbprocedure.
With live view it should take one button.

I look forward to working my way through your link, everyday is a school day and all that.

Cheers