Shooting Through: Use Depth of Field to Eliminate Foreground Obstructions

Depth of field techniques can create some magical effects, from making soft, pleasing backgrounds in portraits to having everything from a foot to infinity appear sharp throughout the frame in landscape work. One of the tricks that can be played with aperture settings is to eliminate distracting foreground elements by focusing “through” them while using a wide open aperture setting to create a shallow depth of field. This can be used to “eliminate” bars at a zoo, a chain link fence at a baseball game or, in this illustration, a rope that surrounded a merry-go-round in Madrid, Spain.

The ride was closed for the winter, and the owners had surrounded it with a rope fence to keep kids from hopping on and playing inside (though knowing kids you can be sure they found a way through!) To illustrate this technique, two equivalent exposures were made with the same lens from the same point of view. The lens is set on manual focus and focused on the closest horse. (Autofocus might have “snagged” on the rope.) A fast lens with a maximum aperture of f/1.4 was used. The first exposure was f/11 at 1/60 second (above) An equivalent exposure was made at f/1.4 at 1/4000 second (below). Note the very soft background. In essence, the very wide aperture setting put the rope so out of focus that it “disappeared.”

Settings: 50mm f/1.4 lens. Both images focused on the foreground horse. Right: f/1.4 at 1/4000 second. Above: f/11 at 1/60 second.

Depth of Field

The aperture setting determines the “thickness of the pipe” through which light flows, thus the volume of light and exposure. But as, if not more importantly it influences depth of field, thus plays a major part in creative focusing decisions.

You can think of depth of field as a grid of distance markers from the front to the back of your photo, sort of like a football field. When you make different aperture settings you are influencing how sharp objects at the ten, twenty, thirty yard lines, etc, will be. You are also influencing how sharp they will be in relation to the point or distance you actually have focus set.

Some settings will make the difference of sharpness between, say, the ten and thirty yard lines quite dramatic, and others will make it less so, and others will eliminate any sharpness difference between those distant points.

How can we control the fact that this image shows sharp foreground trees as well as the massive falls miles away? That’s the kind of control depth of field gives you. With a 24mm lens, exposure at ISO 250 was f/9 at 1/125 second.