Cary Wolinsky and Bob Caputo have a combined 64 years of experience photographing stories for National Geographic and other publications. Along the way, they learned a thing or two about making photographs. In 2010, they launched PixBoomBa.com, which, through videos and illustrated text, imparts photo-making tips with insight, humor, and varying degrees of success.

It’s good to have a little perspective—to know where you stand and just how big (or small) your world and the things in it are. Most pictures we see include something we recognize—a person, a house, a car, or something else that we already know the size of. Like leaves. We think we know what size leaves are. And usually we’re right. But the man in the picture above makes us go, "Whoa, those leaves are really huge."

Even if the rest of the photograph is of something we have never seen before, one familiar object gives our minds a clue and we can then easily work out the sizes of everything else. That’s why you often see pictures of fishermen holding up their catch—we know how big the fish is by comparing it to a human body. It’s why landscapes are often shot with a person gazing off into the distance. And it’s why jewels, archaeological discoveries, dinosaur bones, and the like are often photographed with a ruler, a coin, or some other easily recognizable item. Scale.