So you're driving home from work one day, and your DSLR is sitting in the passenger seat next to you. It just stopped raining and the light is amazing - so amazing that you're tempted to pull over and take a photograph. Then you see it: a real reason to stop and take a photo. A rainbow has appeared in a nearby field, just between a red barn and a couple of cows. You stop your car and lift the camera, but for some reason the rainbow looks faint - almost non-existent - in your viewfinder. You snap the photo anyway, but the rainbow looks faint on the image, too. You look up - the rainbow still looks as brilliant as it did before, but for some reason it's avoiding your camera. What did you do wrong?
[ Top image Peña cabarga y Arco iris. by Flickr user www.josemiguelmartinez.es]
That elusive rainbow
It's not only difficult to capture that pot of gold at the end of a rainbow, it's also difficult to capture the rainbow itself. That's because rainbows aren't solid - they're made when sunlight reflects off of drops of water in the atmosphere. And because they aren't any brighter than the sky, capturing one with your camera can be really tricky.
Some Useful Equipment
If you have a polarizing filter in your bag when you spot that amazing rainbow, try experimenting with it to see if you can change the rainbow's color saturation or make it stand out more from its surroundings. It probably won't take a whole lot of polarization to bring out the colors, and too much may actually make the rainbow disappear, so experiment and don't overdo it.
Also try changing your focal length - remember that that particular rainbow is only going to appear one time, and it may not stick around for long. Use your zoom lens to get close to it - if you can see either of its end points, zoom in there. Then use your wide angle to capture the whole scene. Depending on any obstructions, you may be able to capture both end points in a wide angle shot, which will make for a very compelling image.
A tripod may also be useful - rainbows tend to appear on darker days, and you'll probably want to photograph them with a small aperture. This means of course a slower shutter speed, which also means that you'll find a tripod useful. And of course a cable or remote release will help you prevent camera shake as well.
Finally, you may find a camera with manual exposure and focus settings to be useful when photographing rainbows. Your autofocus won't lock on a rainbow, because it doesn't have a highly defined edge. And a manual exposure (or at the very least, exposure compensation) will allow you to slightly underexpose your subject. This will help saturate the rainbow's colors and make it stand out more.
Pay attention to what is behind the rainbow
You can't get closer to a rainbow - it's an optical illusion, after all, and it will always seem to be the same distance from you regardless of whether or not you move towards or away from it. But you can "change" its position by walking parallel to it. This gives you some flexibility with your foreground and background. My walking, you can move the rainbow's end to wherever you think it will look best in your shot.
Backgrounds are important in all kinds of photography, but particularly when you are photographing rainbows. Because rainbows aren't particularly bright, they need to be photographed against darker backgrounds. Dark clouds make an excellent background, but any dark background will do in a pinch. This will make the rainbow stand out and more closely resemble what you see with your eye. A very pale or bright blue sky will make the rainbow appear faint, which will make for an underwhelming photograph.
Foregrounds are important, too, especially foregrounds that lead the viewer's eye into the photograph and towards the focal point: the rainbow. And like any landscape, you need a strong foreground element to provide dimension to your image. A well-considered foreground can really help make your rainbow pop.
Break some composition rules
If you can see both ends of the rainbow, center it in the frame. This is one of those times when it's appropriate to break that rule of thirds. Of course if you can't see both ends of the rainbow, you'll probably want to go back to that rule of thirds. Have the endpoint fall into one of those rule-of-thirds intersections.
Shoot anywhere, and keep shooting
If you discover that rainbow photography is something you're good at, and interested in pursuing, you're going to need to be prepared to shoot at any time in not necessarily pleasant conditions. A rain sleeve might be a good thing to keep in your camera bag, just in case that rainbow appears in rainy conditions. On days with rain in the forecast, keep your tripod, a polarizing filter and the right lenses in your car, and get ready to jump out (after parking of course) when the sun peeks through and a rainbow appears.
Bows by Flickr user Nicholas_T
Even though you may have some difficulty capturing a faint rainbow, you should shoot it anyway. It may grow brighter while you're standing there - and even if it doesn't, shooting in RAW may give you the ability to brighten it and intensify the colors in post-processing.
Some tips for finding rainbows
Maybe you like rainbow photography so much that you're not willing to wait for one to show up. There are a few things you can do to find a rainbow when the conditions are right. Remember that rainbows usually appear right after a storm, when there is still a lot of moisture in the air and the clouds are just beginning to break up to allow the sun through. If a rainbow is in the works, it will appear in the sky opposite from where ever the sun is. You are also more likely to see rainbows when the sun is low in the sky - either in the morning or the evening. (Yes, the magic hour applies here, too.) Rainbows may also appear in the mist at the base of a waterfall, so you don't necessarily need rain to find a rainbow.
Photographing rainbows has a lot to do with luck and a lot to do with timing. When you see one, you'll need to work fast because the opportunity to capture that shot may be a brief one. Be ready, and be fast.
Need more inspiration? See 25 outstanding waterfall images.
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