Flare – the Contrast Killer

Some of you who are familiar with my photography know that I like shooting into the sun sometimes.  I love being able to get those beautiful sunstars right as the sun hits the horizon (see here for an example).  This is especially challenging as you only get about 30 seconds before the sun is gone and the beautiful sunstars are no longer available.  Sunstars occur due to optical phenomena inside of your lens and you must use a smaller aperature (f/16 or f/22) to achieve this effect.

I tend to bracket exposures in tricky lighting situations so that I can properly expose for the highlights (in the example shown below, the sunset in the background) and for the shadows (the bush with the white flowers).  I can then easily combine these two images in photoshop later by simply layering the darker shot on top of the lighter one, using a layer mask to reveal the shadows.  This is similar to what a Graduated Neutral Density (aka ND Grad) filter does – a technique that on film was mastered by the late, great Galen Rowell.  Shots can produce a very natural looking image, in many cases more natural than an ND Grad, when blending well (luminosity masks are the key to this).

Now the problem with shooting directly into the sun is that the light bouncing around in your lens will lead to strongly reduced sharpness and contrast, resulting in a flatter, lower quality image.  It is important to remember that lens flare does not just lead to funky colored orange spots (aka ghosting), but significantly degrades image quality as well.  On a recent shoot I decided to to test just how strong this effect is by shooting two shots: in the first shot I simply exposed for the shadows and in the second shot I took the same exposure but covered the sun with my fingers.  By covering the sun, I strongly reduced the effects of lens flare and greatly increased the quality of the image (note: covering the sun is not an issue if you use another shot for the sky exposure).  See the examples below for an illustration of the benefits of avoiding lens flare.

NOTE: these images would be blended later with an exposure for the sky, hence why the the sky is totally blown out.  They are also slightly underexposed, but that’s okay because they are here to serve the point of this lesson (flare is EVIL).  Don’t judge them on their artistic merit.  =)

Exposure for Sunset

Exposure for Sunset - This would be blended with the foreground image in Photoshop to acheive the desired dynamic range (an ND Grad also could have been used).

With Flare - Shooting into the sun gives you strong lens flare but ALSO reduces overall image contrast.

With Flare - Shooting into the sun gives you strong lens flare with ghosting but ALSO reduces overall image contrast.

Without Flare - Covering the sun reduces flare and greatly increases contrast, sharpness, and overall image quality.

Without Flare - Covering the sun reduces flare and greatly increases contrast, sharpness, and overall image quality.

100% Crop (from center) with Flare

With Flare (100% Crop from center) - Note the ghosting and general low contrast.

With No Flare (100% Crop from center)

With No Flare (100% Crop from center) - Note ghosting no longer seen AND contrast looks much better.

The above images show just how much ghosting and flare can RUIN your image quality.  Note that the loss of contrast is not just in the center or where the ghosting occurs; the loss of contrast occurs throughout the image.  The examples below, taken from the bottom edge, illustrate this point.

With Flare (100% Crop from center)

With Flare (100% Crop from edge) - Note the low contrast.

With No Flare (100% Crop from edge)

With No Flare (100% Crop from center) - Note the better contrast.

You CANNOT get this contrast back by bumping up the contrast sliders in Lightroom or by using the Curves tool in Photoshop.  You certainly can get some of the contrast back but it will not look as natural as the image with no flare.

Options for reducing flare:

  1. Do not shoot into the sun.  This is the LEAST FUN option =).
  2. Cover the sun with your hand and blend exposures.  This will result in an image without flare but with your hand in the shot.  If you’re blending in a sky that is usually not an issue.  If you are not blending a sky in then you can simply take the same shot with the flare and blend that image with the image without flare.  Using this method you will likely still have flare in a small portion of your image (where your hand was covering).
  3. Use Multi-Coated filters or no filters at all.  Multi-coated filters cost more but are much less prone to flare.  If you buy these try to get them multi-coated on the front and the back.
  4. Use an ND Grad filter.  I have heard that using an ND Grad to lower the incoming light from the sun can lower the effects of flare.  I have yet to test this specifically.  Blending a flare and non-flare image would probably result in the best result when using an ND Grad.

Here’s another image from the same night, after my two image blend in Photoshop.  I show this image because I like the vertical crop better.  Note that there is no sunstar here due to light scattering/diffusion from those low level clouds.

Sunset from TreePeople in Santa Monica Mountains in Los Angeles, CA.

"Reaching Up" - Santa Monica Mountains, Los Angeles, CA

(As a funny aside, I recently read my manual for my new Nikon 24-70mm lens, which stated that you should never shoot with your lens pointing towards the sun since this could lead to your camera catching on fire.  LOL!  Perhaps this is how the great Yellowstone Fire of 1988 started – pyrotechnics from someone’s Pentax 645!  I’ve never actually heard of this happening so hopefully I won’t be the first to lose their camera this way.)

~ by aaronburdick on June 23, 2009.

One Response to “Flare – the Contrast Killer”

  1. Great post!

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