How to avoid lens flare and get a perfect sun star
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I love to include a sunburst or sun star in my images. Sun star gives that special wow to an image and draws the eye to that area. It works best when the sun is low in the horizon such as in the late afternoon, sunset and sunrise. Covering the sun partially with a cloud, mountain or a tree branch can reduce the flare.
You need a very small aperture of at least F14 to capture the radiating beams of the sun. The light rays are created by light diffraction (bending of light) at the aperture blades at these smaller F stops.
Include the sun in the upper third of the image for better composition.
Sometime sunstars can occur even at F8 under certain conditions.The image below was taken at Great fountain Geyser , Yellowstone in a late afternoon. The camera F stop was 8. I used a 14mm lens and a polarizer and was surprised to see a nice sunstar. That was created by the low angle of the sun and the sun light filtering through all of the mist from the erupting geyser.
Larger version can be found here http://harshaj.smugmug.com/Locations/Yellowstone/i-bNCgv8J/A
The shape of the sunstar is influenced by the number of blades in the lens and the shape of the aperture of a given lens. Some lenses are known to create better sunbursts.
Unwanted effect of shooting directly into the sun is the lens flare.
The flare is caused by light reflections inside the lens itself. Many factors contribute to this.
1. Certain type of lenses are more prone to this. High quality lenses have many anti reflective coatings applied to the surface that reduce the flare. Nikon uses a Nano coating and fluoride coating to reduce the flare and Canon lenses have similar coatings.
2. Presence of a protective filter such as a UV filter can make the flare worse. Remove the filter to reduce that.
3. The best way to avoid the flare is to use the lens hood provided with the lens. This significantly reduces the flare by preventing stray light from entering the lens.
4. Dirt on the lens makes the flare worse and a clean lens goes a long way to avoid this.
In spite of all the precautions mentioned above, you can still get lens flare. Of course if you hide the sun behind a tree or mountain in your composition you’re not going to see the flare but then that beautiful sun star is not going to be in the image.
There are few things you can do to help the situation.
Use a piece of cardboard or your hat as an extension of your lens hood. Experiment with the angle to shade the lens while looking through the view finder. When you don’t see the flare press the shutter.
Changing the angle of the camera may also help.
Another trick that works is to take a shot with the flare and take another shot placing your finger in front of the sun to cover it. As longs as the composition hasn’t changed the two shots can be combined later. This works best for me.
Here is how this is done. The image is not a great shot and was shown here for demonstration only. Here is my first exposure shooting directly into the sun. Noticed the flare.
The next shot was taken with a finger to cover the sun. This significantly reduced the flare but you still can see it.
I combined the two in PS and did some minor correction to get the final image shown below. It still shows my sloppy work with healing brush tool but you get the idea.