Finding a rainbow is perhaps the most difficult part of the task. The rainbow appears only in certain conditions and the nature chooses to show them very rare. So, if you are on a rainbow hunt make sure to look for them around waterfalls, fountains and sprinkles.
The background is very important for this type of shot. The rainbows are not solid so they will have to be captured on a background that will enhance their appearance.
Ideal for this purpose would be a blurry background filled with dark colors (dark clouds, mountains, rocks). There are situations in which you cannot change the background but you can modify the angle from which you take the shot, focusing it on the part of the rainbow visible on the best background.
The composition of this type of picture will require a lot of attention. The rainbow is a spectacular phenomenon but the surroundings can enhance its beauty.
As positioning goes, it is very important to accurately frame the rainbow and the scenery inside your picture. Consider the main attraction points and keep in mind the rules of the composition.
The space limits of the rainbow – the places where the rainbow reaches the earth and the sky – are very important and you must capture them inside the photo.
Lenses used for such a photo can be very different. You can experiment using several types so you can see which one gives the best result. The wide angle lenses can offer you very impressive images but also the focalization on a certain point. The focus must be placed on the points where the rainbow intersects different composition elements.
Multiple rainbows are a rare event. If you happen to come across one or to meet a rainbow that has an extra layer, make sure you capture both and your picture will become even more spectacular.
If you own a polarizing filter, try and experiment with it and see what kind of effects you get. In the picture will appear different color saturations, reflections or contrast levels which can influence the image and underline the rainbow.
You should know that some apertures can have a small impact on the rainbow. If you choose a small aperture, the image will have a larger depth bringing the subject even more in the center of attention.
When shooting the landscape, the camera must be steady and this is even more important when you capture a rainbow. So remember to take a tripod with you when you go hunting for rainbows.