I shot some examples to show a friend, who suffers from slight colour blindness, how a Custom WB differs from AWB.
And I thought some members might be interested to see the difference; particularly as some are starting to experiment with macro photography.
These are straight from camera with only a resize and slight sharpen.
And with a Custom WB set from a grey card.
Don't worry about the composition etc, I deliberately chose a difficult subject for colour balance. There was a slight bit of negative exposure composition used to set a better exposure for the flowers.
I normally shoot Raw which does give a second chance for WB change; and sometimes I want something which isn't strictly correct but is a fraction warmer or cooler.
On most general shots, AWB usually makes a fairly good job of the colour settings.
Where I find a particular potential problem is with flower photography where I need a reasonably accurate reference. Otherwise, once I try to edit the images a couple of days later I am wondering if a flower was really that colour. And if not what should I do to get a natural result.
This is where Custom WB really makes a difference.
And, of course, if shooting Jpeg getting your colour balance correct at the time of shooting really does make a difference.