Originally Posted by LJH
I get it at 4 seconds. Or 6. Or 5, as you wrote, depending on where I decide 2 seconds lies and where the intersection point is. Hardly accurate. At best, it is an indicative graph.
I avoided rubbish graphs and shot with it. I also looked at dark locations shot on Ektar Google Images and explored the Shooters' descriptions.
It is easier to read the graph if you print it with a grid. I can send you a file if you like.
I like the idea of looking on Google at images and seeking the information from there.