In Kentucky Horse Park, I learned something else about flash. It was something I thought of randomly, so please mind the poor angle. I don't even remember what this was...I think a poster of a horse race in Louisville, but it was not the Derby.
There were these spot lights on the posters that when I took a picture there was a glare on the posters.
Then I added flash which reduced the glare. Somewhat better, even though the pictures were random snap shots. But still, I learned something.