Depth of field refers to the zone of acceptable sharpness within a photo, stretching from the closest to the farthest in-focus elements. This visual effect is controlled by three main photographic variables: aperture size, lens focal length, and shooting distance. A wide aperture, a longer focal length, or moving closer to your subject will dramatically narrow this sharp zone to isolate the subject against a blurry background. Conversely, narrowing the aperture, using a wide-angle lens, or moving farther away will expand the focus to keep the entire scene clear from front to back.

More often than not, I use a shallow depth of field to isolate a subject and blur out all the surrounding distractions. Occasionally, however, the goal is to get the entire image in focus.

Today, I practiced a technique called focus stacking, which will allow you to get crisp focus over the entire frame. To do this, I took 24 images of the pictured crab shell, each one focused at a progressively deeper depth in the image. Then I used software to merge all of the images into one using the sharpest areas of focus from each. Pictured above is the stacked image. Compare it to the single image below by clicking on each and see if you can spot the difference.