The first challenge in finding a rainbow is finding one to photograph in the first place. Any rainbow requires two elements, light and water droplets. The light needs to be from small source and very bright, so it’ll usually need to be direct sunlight (although it is possible to find and photograph “moonbows”) they’re very hard to see and even harder to capture well. The need for both sunlight and rain or mist means you’ll usually need to look for rainbows in mixed weather (rainy conditions without complete overcast) or in other places where mists form in broad sunlight (waterfalls, such as my Iceland image above, geysers, and the like.)

The physics of rainbows shows that when they appear, primary rainbows will always appear at angles about 140 degrees from the sun, in other words, you’ll want to look for rainbows not so much toward the sun as away from it. This figure has one important implication for nature photographers, unless you can see down for a long way (into a deep canyon, or down from a mountaintop or airplane) you won’t be able to see a rainbow in the sky when the sun is high. At moderate latitudes, your chances for rainbows will be limited to the beginning and end of the day. As you move closer to the poles, the sun stays low longer (if there’s sun at all!), and opportunities increase.

Because rainbows aren’t physical objects but reflections from water droplets, it is possible at times to “move the rainbow”, as you move your point of view, the rainbow appears to move relative to the objects in front of and behind it, so long as there is in fact a rainbow visible from the new location. In some situations this will allow you to move the rainbow within the composition, perhaps for the better.

Bringing out the subjective intensity of rainbows seems to require care, all too often snapshots of rainbows lack the punch they seem to have in person. Polarizers (turned correctly) will help here, almost doubling the intensity of the rainbow relative to the scene around it, and are a great place to start. Proper exposure is also critical, as the most saturated rainbow colors will occur if the rainbow is exposed for the midtones, too light or too dark and the colors will muddy up or fade.

One final bit of advice, it is all too easy when one sees a great-looking rainbow to try and photograph it alone, for it’s own sake. While you’ll be able to get some pretty snapshots that way, in general those images rarely seem “great” when you’re done with them. Instead, look to combine rainbows with other elements of the scene, whether as a wide landscape, or as a more abstracted detail shot such as the one at the top of this article, you’ll find those images have a greater potential to really sing.

The rise and fall of the ocean along the shore is affected by three factors, the gravitational influence of the sun, of the moon, and the shape of the shoreline and sea floor. Historically, tidal prediction was a difficult problem, even today, tides at a given location are not so much computed from first principles as they are modeled in part based on records of past tide levels. Fortunately, you don’t have to get into the tidal prediction business yourself, many tidal prediction resources exist.

It is helpful to build up a bit of intuition about tides. In any given day, the tide will cycle up and down, often by seemingly unpredictable amounts, twice. So the basic pace of rhythm of tides is measured in hours. How much tides vary at a particular location varies both over the lunar month and over the year. In each month, the greatest tidal variation happens at about the time of the full moon or the new moon, as such, I plan a lot of my longer coastal trips to conincide with the full moon, both for the full moon itself and for it providing a greater range of tides to photograph in. There’s also variation through the year, the lowest low and highest high tides are those nearest early January and early July (earth’s perihelion and aphelion, but don’t worry, that won’t be on the quiz!). In short, I find that the full moons, particularly near the beginning and middle of the year offer some of the best times for coastal photography.

Today, detailed tide predictions are not hard to find. Many web sites provide tidal information, such as the NOAA Tides and Currents page, which covers the United States, it’s not hard to find other sites for many locations. These web pages work well if you plan ahead or have an internet connection where you’re going to be photographing.

Another great resource for tidal predictions is the annual Tidelog graphic almanac from Pacific Publishers. By providing tide information for different areas in a week-at-a-glance graphic format, as well as sunrise/sunset, moonrise/moonset and phase information, it’s remarkably easy to pick great times for coastal photographic trips by flipping through pages and scanning for deep tides quickly.

With the growing popularity of smart phones there are a handful of tide prediction applications available as well. For Palm OS-based devices, TideTool is my favorite choice, as it offers graphic tidal predictions and works just as well offline (that is, when your phone doesn’t have a signal.) Tide App for Apple’s iPhone platform is also a good choice but doesn’t (yet) offer offline prediction. I haven’t used cTide for PocketPC devices, but it has been recommended to me and also offers offline prediction.