While the sun is generally incredibly useful to photographers, it can occasionally be annoying. If the sun hits your lens at an undesirable angle, you can end up with spots or flares that ruin a shot. Flares generally take on a geometric shape, and may be easy to miss while shooting. Additionally, a flare can significantly reduce the amount of contrast and saturation in your image.
The flare is typically caused by a very bright light sources (in most cases the sun). Flares are far more common in zoom lenses as they have multiple surfaces that are prone to light scatter. With a little practice you’ll learn to spot flares quickly. Getting rid of flares just requires a few strategies and modifications to your shooting style.
Use a Hood
Most lenses include a hood attached at the end of the lens. Typically, the hood is reversed for shipping (to make the lens shorter and easier to pack). Unfortunately most people never bother to turn the hood around.
Once a lens is mounted to your camera, you should properly set the hood. With a quick turn (and perhaps a push of a release button) the hood can be removed. Reverse its direction and re-attach it to your lens in order to protect the lens from flare.
Hoods are usually specific to each lens. Some will have notches (called petals) to better accommodate the aspect ratio of your camera’s digital sensor. These type have an angle of view which is greater in one direction than the other . Others will vary in length to avoid casting a vignette in your final image.
If you lose your hood, I recommend you purchase a replacement. The hood is the best way to cut down on flares. It can also help protect the front of the lens from accidental impact as well as contact smudges.
Keep the Lens Clean and Clear
Most lenses have an anti-reflective coating to cut down on lens flare. Of course greasy fingerprints and other smudges can also cause their own problems. When you clean the lens, be sure to use a proper lens cleaning cloth to remove smudges without damaging this coating.
If you’re going to use additional filters on your lenses (such as a protective UV filter or a neutral density filter) make sure you don’t skimp on quality. Cheap filters often lack good anti-reflective coatings). These filters can often cause flare through the introduction of additional reflective surfaces. If using filters, make sure you choose a quality that matches your lens.
Flag the Lens
One way to prevent lens flare is to block the light. Typically the flare is caused by light entering from the side of the frame. This light is rarely needed for a proper exposure and can be blocked. If using a tripod, you can place your body to the side of the lens to serve as a wall. You can also reach out with a hat off to the side to block the light.
You can of course use other devices to block unwanted light. I’ll often attach a Rogue FlashBender right to my lens (http://www.expoimaging.com). These flexible cards are normally used to shape an off-camera flash, but I find the built in flexible support rods bendable surface works well to flag a troubling flare.
Change your Position
If you can’t minimize a flare, you have one simple recourse. Move your camera until the flare is gone. Remember flare is caused by light hitting the lens at an unwanted angle. Often a little adjustment can be very effective at removing the flare. You can look to frame the shot so objects are blocking the sun or light source (or even reposition your subject to block the light for you). You may find that tilting or panning the camera just a few degrees can remove the flare.