Who doesn’t love rainbows? Rainbows are a favorite of nature photographers, and for good reason. Not only are they beautifully vibrant, representing all colors in the spectrum that can be seen by human eyes, but their graceful arcing shapes add compositional interest to photographs. But finding rainbows is a tough business, and doing them justice even tougher. So, what is the best way to photograph a rainbow? This tutorial contains a few tips to optimize your chances of getting great rainbow photos.
But first: what is a rainbow? A rainbow is a meteorological phenomenon that causes a spectrum of light to appear in the sky when the sun shines onto droplets of moisture in the atmosphere. Rainbows take the form of a multicolored arc, with red on the outer part of the arc and violet on the inner section of the arc. A rainbow that forms at sunrise or sunset will often look more red than multicolored. Sometimes, a dim secondary rainbow is seen outside the primary bow. Known as a “double rainbow,” such secondary rainbows are caused by a double reflection of sunlight inside the raindrops. Because it is a second reflection, the colors of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. Although I’ve never seen it happen myself, old timers often spin yarns of seeing a rainbow reflected two or three times in the sky. Multiple rainbows are rare, but they do happen—if you see one, shoot first and ask questions later!
1. When it rains, be ready. Rainbows need two key ingredients: moisture in the atmosphere, and sunlight. Your best chances of seeing a rainbow are during or right after a rainstorm. You don’t need to get rained on to see a rainbow (although it certainly doesn’t hurt your chances)—as long as there is rain falling nearby, you might see a rainbow. Conditions most conducive to rainbow formation are a period of rain followed by sudden clearing in the direction of the sun. If sunlight breaks through the clouds while there is still significant moisture in the sky, a rainbow might form.
2. Turn your back on the sun. Rainbows always form in the sky opposite the sun’s position. If it is raining and you can see the sun, then chances are you’ll see a rainbow, if not right away then as the rain begins to clear. Turn around and get ready!
Rainbows vary in intensity. Faint rainbows will not show up all that well in photographs. When you see a rainbow, no matter how faint, start shooting—a rainbow may start off weak, but increase in color and intensity over time. Make sure that you take as many photos as possible during peak intensity.
3. Make the rainbow part of your overall composition. When photographing rainbows, you basically have two options: photograph just the rainbow, or make the rainbow an element of your overall composition. If you choose the first option, a telephoto zoom lens may be your best choice, allowing you to get in close. If you choose to include the rainbow as a part of your overall composition, a wide-angle zoom lens is best.
Everyone knows that the endpoints of a rainbow (where the rainbow terminates at the horizon) are great places to find leprechauns with their pots of gold. More relevant to this discussion and to reality, the endpoints of a rainbow are also places of compositional power and interest. Make sure to include at least one endpoint in your composition. You will need a very wide-angle lens to be able to include both endpoints and the entire arc of the rainbow simultaneously.
It is best to photograph a rainbow against an uncluttered and dark background, if possible. Gloomy storm clouds and dark mountain peaks make great backgrounds. If working with a wide angle lens, look for an interesting foreground to add to the composition. Ideally, the shapes of foreground elements should somehow relate or lead to the rainbow itself. If you include foreground elements that are close to the camera, you may need to select a small aperture (such as f/11 or f/16) to ensure that you have sharp focus throughout the picture.
Your choice in composition when photographing a rainbow often depends on how much of the rainbow you can see. Often, only part of the rainbow will be visible. If you are lucky, you will see the entire arc of a rainbow. If you can include the entire arc in your photograph, centering the rainbow is appropriate, although consider placing the rainbow and the horizon in the upper third of the image frame. If you can see only a portion of the rainbow, consider placing the rainbow’s endpoint in either the left or right side of the picture, away from the center. Having the rainbow arc into the scene is typically better than having it arc out.
4. Polarize for maximum effect. A polarizer filter can help bring out the colors of the rainbow. But, you ask, aren’t polarizer filters supposed to remove reflections? Aren’t rainbows reflections in the sky? Although both are more or less true (a rainbow is really more refraction than reflection), if you polarize only slightly or keep the polarizer in the “non-polarized” position, you can actually intensify the colors in the rainbow, rather than remove them. Experiment with the polarizer, turning the filter until you get the desired result. Avoid full polarization, as it may remove the rainbow from the sky.
Although I tell my students to always use a tripod for nature photography, this holds doubly true for rainbows. Rainbows often form during stormy periods with low light, and if you are using a polarizer filter and a small aperture for depth-of-field, your exposures will likely be too long for hand held photography. A tripod is a must if you want sharp images.
5. Don’t just look to the sky for rainbows. Rainbows can also form in the spray of waterfalls, geysers, and ocean surf. As with sky rainbows, spray rainbows only form when sunlight is shining. However, they are more predicable than sky rainbows, as rain is not necessary for them to form—they have their very own steady source of moisture. Look for spray rainbows at the base of waterfalls with relatively open exposure to the sky when the sun is shining high during mid-day. Because you are working with mid-day light, be aware that you will likely encounter a significant amount of contrast between sunlit and shadowed portions of the scene. Expose carefully to ensure that your highlights are not overexposed, letting shadows turn to pure black if necessary. Consider isolating portions of the scene to avoid areas of excessive contrast.
When working on the shore, look for spray rainbows on days when the surf is extra choppy. Heavy and gusty winds will often lift spray off of the crests of incoming waves, and if you have the sun at your back, you will see spray rainbows. A telephoto lens will allow you to get in close to the action. These rainbows are very short-lived; select a continuous shooting mode and fire off a quick burst of shots whenever you see a spray rainbow form.