Thursday, February 27, 2014

Stormy Skies

Dramatic skies make for dramatic photographs. And what gives the sky drama is clouds. They can be light and puffy, or dark and threatening as in this image.

Even dark clouds can have very bright areas that can be difficult to expose properly. This scene includes dark clouds, a bright area of clouds, and sunlit and shadowed foreground. The contrast range was extreme. As many of you already know, I am not a big fan of HDR, and I prefer to use Lightroom to control extreme highlights and shadows. Of course the basic exposure has to be fairly accurate, which keeps the dark tones and light tones within controllable limits.

In difficult lighting situations, always ALWAYS (and did I say always??!) check the histogram after every few shots, especially in changing conditions. It is virtually impossible to guarantee accurate exposures without relying on the histogram to provide invaluable information.

If the histogram “graph” has information jammed up against the right edge of the histogram box, that is an indication of overexposure. If it is against the left edge, it indicates underexposure. Overexposure is also shown by the “blinkies,” those areas that flash black on overexposed white areas in the image. If the blinkies show only in small areas, it is usually OK to leave the exposure as-is. If, however they appear in large areas like bright clouds, white birds, or other significant areas of the image, then it is wise to use exposure compensation to reduce exposure by 1 to 2 stops. Your camera's Owners Manual explains how to employ exposure compensation.

After you have set the new exposure, take a shot and again look at the histogram. If the blinkies are gone and the dark areas are not too underexposed, your exposure should be fine. If issues still exist, refine the exposure compensation settings, take another shot and again check the histogram. Do this until you have hit on the best compromise. Then do the final refinements in post-production with Lightroom, or Camera RAW in Photoshop, or other image optimization software you have access to.

Shutter Speed 1/320 sec.  Aperture f/20.  ISO 400.  Lens: Canon 17-40mm f/4L, set to 26mm.  Camera: Canon 40D.  Gitzo tripod with Really Right Stuff ballhead.

TODAY’S QUOTE: “Heavy hearts, like heavy clouds, are best relieved by the letting of a little water.”  --Christopher Morley

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