In this day of ubiquitous cameras, automatic exposure, and free information, a creative photographer’s surest path to unique images is achieved by managing a scene’s depth. Anyone with a camera can compose the left/right/up/down aspect of a scene. But the front/back plane, a scene’s depth, that we human’s take for granted, is missing from a two-dimensional image. Managing depth requires abstract vision and camera control beyond the skill of most casual photographers.
While skilled photographers frequently go to great lengths to maximize depth of field (DOF), many forget the ability of limited DOF to:
- Guide the viewer’s eye to a particular subject
- Provide the primary subject a complementary background
- Provide background context for a subject (such as its location or the time of day or season)
- Smooth a busy, potentially distracting background
- Create something nobody will ever be able to duplicate
They call it “bokeh”
We call an image’s out of focus area its “bokeh.” While it’s true that bokeh generally improves with the quality of the lens, as with most things in photography, more important than the lens is the photographer behind it. More than anything, achieving compelling bokeh starts with understanding how your camera sees the world, and how to translate that vision. The image’s focus point, its depth of field (a function of the f-stop, sensor size, focal length, and subject distance), and the characteristics of the blurred background (color, shapes, lines) are all under the photographer’s control.
No special equipment required
Compelling bokeh doesn’t require special or expensive equipment—chances are you have everything you need in your bag already. Most macro lenses are fast enough to limit DOF, have excellent optics (that provide pleasing bokeh), and allow for extremely close focus (which shrinks DOF). A telephoto lens near its longest focal length has a very shallow DOF when focused close.
Another great way to limit your DOF without breaking the bank is with an extension tube (or tubes). Extension tubes are hollow (no optics) cylinders that attach between your camera and lens. The best ones communicate with the camera so you can still meter and autofocus. Not only are extension tubes relatively inexpensive, with them I can focus just about as close as I could have with a macro. They can also be stacked—the more extension, the closer you can focus (and the shallower your DOF). And with no optics, there’s nothing compromise the quality of my lens (unlike a teleconverter or diopter). But there’s no such thing as a free lunch in photography—the downside of extension tubes is that they reduce the amount of amount light reaching the sensor—the more extension, the less light. On the other hand, since I’m using them to reduce my DOF, I’m always shooting wide open. And the high ISO capability of today’s cameras more than makes up for the loss of light.
Many of my selective focus images are accomplished without a macro or even a particularly fast lens. Instead, preferring the compositional flexibility of a zoom, I opt for my 70-200 f4 (especially) and 100-400 lenses. While my 100 macro is an amazingly sharp lens with beautiful bokeh, I often prefer the ability to isolate my subject, in a narrow focus range, without having to get right on top of it. On the other hand, if I have a subject I want to get incredibly close to, there’s no better way than my macro and an extension tube (or two, or three).
Managing depth of field
When using creative soft focus, it’s important that your background be soft enough that it doesn’t simply look like a focus error. In other words, you usually want your background really soft. On the other hand, the amount of softness you choose creates a continuum that starts with an indistinguishable blur of color, includes unrecognizable but complementary shapes, and ends with easily recognizable objects. Where your background falls on this continuum is up to you.
Your DOF will be shallower (and your background softer):
- The closer your focus point
- The longer your focal length
- The larger your aperture (small f-stop number)
A macro lens and/or extension tube is the best way to get extremely close to your subject for the absolute shallowest DOF. But sometimes you don’t want to be that close. Perhaps you can’t get to your subject, or maybe you want just enough DOF to reveal a little (but still soft) background detail. In this case, a telephoto zoom may be your best bet. And even at the closest focus distances, the f-stop you choose will make a difference in the range of sharpness and the quality of your background blur. All of these choices are somewhat interchangeable and overlapping—you’ll often need to try a variety of focus-point/focal-length/f-stop combinations to achieve your desired effect. Experiment!
Composing a shallow DOF image usually starts with finding a foreground subject on which to focus, then positioning yourself in a way that places your subject against a complementary background. (You can do this in reverse too—if you see a background you think would look great out of focus, find a foreground subject that would look good against that background and go to work.)
Primary subjects are whatever moves you: a single flower, a group of flowers, colorful leaves, textured bark, a clinging water drop—the sky’s the limit. A backlit leaf or flower has a glow that appears to originate from within, creating the illusion it has its own source of illumination—even in shade or overcast, most of a scene’s light comes from the sky and your subject will indeed have a backlit side. And an extremely close focus on a water droplet will reveal a world that’s normally invisible to the unaided eye—both the world within the drop and a reflection of the surrounding world.
My favorite backgrounds include parallel tree trunks, splashes of lit leaves and flowers in a mostly shaded forest, pinpoint jewels of daylight shining through the trees, flowers that blur to color and soft shapes, sunlight sparkling on water. I also like including recognizable landscape features that reveal the location—nothing says Yosemite like a waterfall or Half Dome; nothing says the ocean like crashing surf.
The final piece of the composition puzzle is your focus point. This creative decision can make or break an image because the point of maximum sharpness is where your viewer’s eyes will land. In one case you might want to emphasize a leaf’s serrated edge; or maybe its the leaf’s intricate vein pattern you want to feature. Or maybe you’ll need to decide between the pollen clinging to a poppy’s stamen, or the sensual curve of the poppy’s petals. When I’m not sure, I take multiple frames with different focus points.
Exposing selective focus scenes is primarily a matter of spot-metering on the brightest element, almost always your primary subject, and dialing in an exposure that ensures that it won’t be blown out. Often this approach turns shaded areas quite dark, making your primary subject stand out more if you can align the two. Sometimes I’ll underexpose my subject slightly to saturate its color and further darken the background.
And let’s not overlook the importance of a good tripod. In general, the thinner the area of sharpness in an image, the more essential it is to nail the focus point. Even the unavoidable micro-millimeter shifts possible with hand-holding can make the difference between a brilliant success and an absolute failure.
Virtually all of my blurred background images are achieved in incremental steps. They start with a general concept that includes a subject and background, and evolve in repeating click, evaluate, refine, click, … cycles. In this approach, the only way to ensure consistent evolution from original concept to finished product is a tripod, which holds in place the scene I just clicked and am now evaluating—when I decide what my image needs, I have the scene sitting there atop my tripod, just waiting for my adjustments.