Okay, so that’s pretty basic. How about this one?
Wikipedia: The change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated
Whoa, I hope that’s not on the test.
Who doesn’t love the soothing tranquility of a good reflection? And like a metaphor in writing, a reflection is an indirect representation that can be more powerful than its literal double by virtue of its ability to engage the brain in different ways than we’re accustomed. Rather than processing the scene directly, we first must mentally reassemble the reflection’s reverse world, and in the process perhaps see the scene a little differently.
Reflections are a powerful photographic tool as well. Water’s universal familiarity makes it an ideal subject for photographers frustrated by their camera’s static representation of our dynamic world. Just as we freeze in space or blur a waterfall to express turbulent motion, we can include a reflection to convey serene peace.
Water reflections come in many forms, from a mirror-sharp reverse of a mountain atop a still pool, to an abstract shuffle of color and texture on a choppy lake. Without getting too far into the physics of light, it’s important to understand that every object we see (and photograph) comes to us courtesy of reflected light. For example, when sunlight strikes El Capitan, some of the sun’s photons bounce straight back into our eyes, and there it is: El Capitan!
But other photons striking El Capitan head off in different directions—some are captured by other sets of eyes, and others land on the surface of the Merced River. Some of these photons pass beneath the river’s surface to reveal the submerged riverbed, while others bounce off. The ricocheting photons that travel from El Capitan and bounce off the river, reach our eyes as a reflection. In other words, what we call a reflection is in fact re-reflected light (reflected first from El Capitan, then by the river).
Mirror reflection recipe
The ingredients for a crisp, mirror reflection like the El Capitan image at the top of the page is pretty simple: still water, a reflection subject that’s much brighter than the water’s surface (the greater the contrast the better), and a view angle that matches the angle from the water’s surface to the reflection subject. (The best reflections are usually found on shaded water because there are fewer photons to compete with the photons bouncing from the reflected subject.)
The El Capitan reflection above was a perfect confluence of reflection conditions. Clean, still air, dense shade on the river, and El Capitan’s fully exposed, reflective granite, make early morning the best time for El Capitan reflections. On this April morning I made my way down to the Merced River hoping to photograph the first light on El Capitan reflected in the Merced River. Finding my route down to the river blocked by spring flooding, I was forced to improvise. The morning air was clean and calm, and the ephemeral lake was mirror-still.
Circling the flooded meadow, I found a gap in the trees that opened onto the most complete view and reflection of El Capitan and the Three Brothers I’ve ever seen. So complete in fact, that I couldn’t include it all with my 16-35mm lens at its widest focal length. Fortunately, I was able to borrow a Canon 11-24 lens and Metabones IV adapter from a friend (thanks, Curt!), just wide enough to fit the entire scene at the lens’s shortest focal length.
Playing the angles
Understanding that reflected photons leave the water’s surface at the same angle at which they arrive—imagine the way a tennis ball bounces (if it weren’t affected by spin, wind resistance, or gravity)—helps us get in position for the reflection we want.
A few years ago I found myself atop Sentinel Dome right after an intense rain shower had turned indentations in the granite into small, glistening pools. Rather than simply settle for the vivid sunset coloring the clouds above, I decided to include the sunset reflected in the pools as well. At eye-level the pools reflected blue sky, so I dropped my tripod as low as it would go, almost to granite level, positioning my lens at the same angle to the pools that the red light leaving the clouds struck the water.
When the water’s in motion
As spectacular as a crisp, mirror reflection in still water is, it’s easy to overlook the visual potential in a reflection that’s not crisp, or to forget your camera’s ability to render a soft or abstract reflection much better than your eyes view it. While a crisp reflection often dominates the primary subject in an image, a splash of reflected color or shape can provide a striking accent to a dominant primary subject. And a reflection disturbed by the continuously varying angles of rippled or choppy water magically appears when a long exposure smoothes the water’s surface.
In the image on the right, the El Capitan reflection undulating atop the Merced River was barely perceptible to my eyes. But the reflection came to in a 25 second exposure achieved with the help of 2-stop hard graduated neutral density filter that subdued the day’s last rays on the clouds and El Capitan, and a neutral polarizer (with the reflection dialed up) that cut the light on the entire scene by a couple of stops. And since a reflection is never as bright as the actual scene, using a GND meant I need to do a little dodging and burning in Photoshop.
Where to focus
Another often misunderstood aspect of reflection photography is where to focus. Though it seems counterintuitive, the focus point of a reflection is the reflection subject, not the reflection surface. This isn’t such a big deal in a scene like the El Capitan reflection at the top of the post, where the focus point of everything of visual significance is infinity, but it’s a very big deal when you want both your reflection and rocks or leaves on the nearby water surface sharp.
The El Capitan reflection on the right is very different from the El Capitan reflection above, where the extreme depth of field ensured sharpness had I focused on anything in the scene or the reflection. But here the leaves that were my scene’s primary emphasis were just a couple of feet from my camera, while El Capitan was several thousand feet distant. Even though the leaves floated atop the El Capitan reflection, focusing on El Capitan would have softened the leaves. To increase my depth of field, I stopped down to f/18 and focused several feet into the foreground leaves, then magnified the image on my LCD to verify that all of the leaves were sharp. Though El Capitan is slightly soft, a soft reflection is far more forgivable than a soft foreground.
It seems that reflections often feel like a fortuitous gift that we just stumbled upon. But given that reflections are entirely beholden to the laws of physics, they’re far more predictable than many of the natural elements we photograph. Taking a little time to understand the nature of reflections, and how they’re revealed by a camera, enables photographers to anticipate their appearance.
For example, in Yosemite I know that low flow makes autumn the best time for reflections in the Merced River. On the other hand, when the Merced is rushing with spring runoff, Yosemite’s meadows often shimmer beneath tranquil vernal pools. I plan many trips (and workshops) to take advantage of these opportunities.
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