In this day of ubiquitous cameras, automatic exposure modes, free information, and powerful processing tools (even built into our cameras and phones!), taking a good picture has never been easier. But capturing a great photo, an image with enough uniqueness to stand out from the rapidly expanding crowd, is growing increasingly harder.
It seems that some photographers have decided to attack this problem by risking life and limb to chase increasingly exotic subjects, or by creative computer manipulation. This is great for those with enough time, money, and physical or technical skill, but there are simpler opportunities.
One of photography’s most accessible, yet underutilized, paths to unique images is creative depth control. While anyone with a camera can compose the two-dimensional, left/right/up/down aspect of a scene, managing depth in a two-dimensional medium requires both abstract vision and exposure control that’s outside the comfort zone of most casual photographers.
While photographers frequently go to great lengths to maximize front to back sharpness (depth of field), consulting hyperfocal apps or blending multiple image, many photographers don’t appreciate the ability of shallow DOF to:
- Guide the viewer’s eye to a particular subject
- Provide the primary subject a complementary background that doesn’t compete
- Provide background context for a subject (such as its location, time of day, or season)
- Smooth or eliminate a busy and distracting background
- Create an image that no one will ever be able to duplicate
They call it “bokeh”
We call an image’s out of focus background its “bokeh.” While it’s true that bokeh generally improves with the quality of the lens, as with most things in photography, at least as important as the lens is the photographer behind it.
More than anything, achieving compelling bokeh starts with understanding the difference between your and camera’s vision the world, and how to leverage that difference in your photos. The image’s focus point, its depth of field (a function of the sensor size, f-stop, focal length, and focus distance), and the characteristics of the blurred background (color, shapes, lines) are all controlled by the photographer before the click.
No special equipment required
Compelling bokeh doesn’t require special or expensive equipment—chances are you have everything you need in your camera bag already. Most macro lenses are fast enough (large aperture) to limit DOF, have excellent optics that provide pleasing bokeh, and allow for extremely close focus (which shrinks DOF). But for those without macro lens, a telephoto lens near its longest focal length is very effective.
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 and 100-400 lenses.
One piece of equipment that will allow you to shrink your DOF without breaking the bank is an extension tube. An extension tubes is an empty (no optics) cylinder that attaches between the camera and lens to shift the focus range closer to the camera: with an extension tube you can focus closer, but you can no longer focus to infinity. Make sure you buy extension tubes that (as most do) pass communication between the camera and lens so you can still meter and autofocus.
Extension tubes reduce the lens’s focal range, enabling you to focus closer than you otherwise would. And as you might already know, the closer you focus, the shallower your depth of field. Of course, adding an extension tube to focus closer also prevents you from focusing to infinity (but if you wanted to do that, you wouldn’t have put on the extension tube in the first place).
Extension tubes can also be stacked—the more extension, the closer you can focus (and the shallower your DOF). And because extension tubes have no optics, there’s no glass to compromise the quality of the 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. Fortunately, given the high ISO capability of today’s cameras, you can usually recover this lost light by simply bumping your ISO.
I won’t get too deep into using extension tubes, except to say that getting comfortable with them takes a little (but not too much) practice. I find that I spend a lot of time focusing with the focal length only, or with a combination of focal length and the focus ring. This makes using a tripod even more essential (but you’re already doing that anyway, right?), because with my camera on a tripod, I can have one hand on each.
Managing depth of field
The amount of softness you choose falls somewhere on a continuum that starts with an indistinguishable blur of color that includes unrecognizable shapes, and ends with soft but easily recognizable objects. When using creative selective focus, I usually go for a background that’s soft enough that it doesn’t simply look like a focus error or compete with my subject. In other words, I usually (but not always) want my background really soft.
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, creating the absolute shallowest DOF. But sometimes you don’t want to be, or can’t get, that close. Or maybe you want just enough DOF to reveal a little (but still soft) background detail. In this case, a telephoto zoom lens 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. Or you can do this in reverse, starting with a background you think would look great out of focus, then finding a foreground subject that would look good against that background.
Primary subjects can be 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 can radiate with 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 mini-reflection of the surrounding world.
My favorite backgrounds include things like parallel tree trunks, splashes of lit leaves and flowers in a mostly shaded forest, flowers that blur to color and soft shapes, pinpoint jewels of daylight shining through the trees, sunlight sparkling on water. I also like including soft but 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, in another its intricate vein pattern. 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 can’t decide, 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 the 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 narrower the area of sharpness in an image, the smaller the focus point margin of error. Even the unavoidable micro-millimeter shifts possible with hand-holding can make the difference between a brilliant success and an absolute failure, making a tripod essential.
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.
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