Focus stacked portrait of a lobster fisherman

Control A Photograph’s Depth Of Field With Simple Focus Stacking

Text and Photography by Chuck Place

The commercial fisherman was having a tough time holding up the struggling lobster. It was constantly trying to grab him with the sharp points at the end of each leg. In order to avoid being clawed by the large lobster, the fisherman was holding it out in front of him and that was a real problem for the image I had pre-visualized.

I was photographing a portrait of a commercial lobster fisherman at the Fisherman’s Market in Santa Barbara for a book on local cuisine. It was a foggy morning and I wanted to shoot using a shallow depth of field so that the commercial fishing boats and pier behind my subjects were softly out of focus. In order to separate my subjects even more from the background, I had lit my subjects with a warm, diffused flash.

Everything fell into place—except the lobster. With an aperture setting of f5.6, either the fisherman’s face would be sharp or the lobster would be sharp. If I wanted a soft background, I couldn’t stop down the aperture further and seemed to be stuck with only one of my two subjects being sharply focused.

I used a solution called focus stacking. Making sure that I had frames where the focus on the fisherman’s face was sharp and others where the lobster is sharp, I didn’t change exposure or composition. I merely shifted the focus slightly. This had to be done quickly so that the lobster and fisherman were in pretty much the same position, or in register, in matching images.

Back at my computer, I layered the two shots in Photoshop with the sharp fisherman on top. Setting up a mask on that top layer, I painted out the soft lobster with black, letting the sharp lobster below show through. Flattening the two layers gave me a sharply focused lobster in front of a sharply focused fisherman, all with a soft background created by a shallow depth of field at an f5.6 aperture setting.

Focus stacked photo of bass fishermen on a lake.

Focus stacked photo of bass fishermen on a lake.

Although focus stacking is usually used in macro work, where an extended depth of field is impossible with a single frame, I have found it extremely useful for controlling depth of field in a number of situations where I wanted either shallow depth of field or greater depth of field.

The image of the bass fishermen on Lake Cachuma is an example of layering two images, one focused on the fishermen and one focused on the mountainous background, to give me an image with great depth. Sure, I could have stopped down my lens for greater depth of field, but I had managed to forget my tripod that morning and shooting a 300mm lens hand-held required a wide-open aperture for a fast shutter speed and sharp subjects. Sometimes focus stacking helps me correct rather foolish mistakes. I must have missed my coffee that morning.

All types of focus stacking software can be found with a quick search on-line and some photographers stack multiple frames of the same subject to achieve startling depth and detail in a single image. It’s also a tool that can be applied in subtle ways using simple layering in Photoshop. Experiment with it and see if it doesn’t help in controlling depth of field and producing images that are impossible to capture in a single frame. Remember–mastering post-production tools will expand the photographic possibilities exponentially. As in the days of black and white negatives, digital image capture is only half the journey to a final image. Post-production is the other half. Have fun.

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