High Dynamic Altocumulus

I have not been very happy with the results when I have tried to photograph specific clouds, the camera did not seem to know where to focus so they tended to come out a bit fuzzy.

Today I fiddled with a few other settings and lo! the camera decided it might focus using the High Dynamic setting. I need to look up the manual to find out what this means, however I'm quite content to use it in ignorance, as long as it works.