Make a series of landscape photographers in which there’s a bright blue sky and clouds. In each case, use center-weighted metering, and lock your readings when you make the picture; make one exposure reading solely from the ground, one reading solely from the sky, and one from an average of the two (or reading from the horizon with equal weight in the sky and in the ground area). Compare the exposures, and note when the sky records best.

Adapted from Hands-On Digital Photography by George Schaub (Amphoto Books, 2007, $25)