Tuesday, July 28, 2009
Dialing In Skin Tone
A wedding professional has some sage advice and techniques for mastering elusive skin tones
While the exposure meters in digital cameras are extremely powerful, they’re not perfect, and the wedding photographer especially needs to maintain perfect exposure. That’s why so many pro wedding shooters still rely on the same handheld light meters that were so in vogue in the days of film.
A handheld light meter provides a measurement of the incident light falling on a scene, while the in-camera meters are reflective. Measuring the light hitting a surface is particularly useful because it eliminates the possibility that the camera’s meter is fooled by specular highlights. Bright areas of a scene like the sun, lights and other elements won’t throw off the metering.
Here’s why that’s crucial: If your sensor has only four stops of dynamic range, and the camera’s meter sees a bit of light reflected off of a mirror as being the average highlight, but it’s actually two stops brighter than the white of the bride’s wedding dress, then two stops of dynamic range have been lost to that mistaken metering.
If you properly meter for the highlight of the dress (ignoring the reflection in the mirror), however, then you’ll end up with four stops of detail below that level, preserving all the scene’s contrast.
By examining the in-camera histogram, it’s possible to get a better idea of the tonal distribution in the image. Your histogram (set to Luminance) should ideally be a bell curve with no spikes or gaps, and without having either end of the histogram cut off.
Still, a scene that appears properly metered but suffers from a clipped highlight or shadow needs to be reshot, as it won’t be possible to recover data that has been clipped. It’s possible, however, to adjust contrast with software.
While it would be easy to write an entire book on the subject of tonal correction in digital images, most programs try to simplify the process. They have a variety of tools (highlight and shadow, exposure, contrast, etc.) that all employ different ways to manipulate the same set of information.
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