 Jon K. Tormoehlen |
incident light with hand-held meter why do some photograhers argue that a hand-held meter which measures incident light provides the most accurate film exposure?
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robert G. Fately |
The argument goes like this: A reflected light meter, naturally, is measuring the light being reflected from the subject. Yet without inherent intelligence, the only thing it can do is indicate an exposure that will yield a standard 18% gray shade. While this is fine for most applications, if you take a photo of a polar bear in the snow or a black kitten on navy velvet the what the meter indicates will lead to underexposure, or overexposure, respectively. Knowing this fact, the wise and experienced photographer shooting that kitten knows to take the meter reading and then underexpose by a stop or two to avoid getting a grey kitten on lighter gray background. Incident reading is done from te vantage point of the subject - thus the actual amount of light actually falling on the subject is actually metered. That the subject may be white on white or whatever matters not - the meter will always indicate an exposure value based on the light hitting the subject. Thus, no adjustments need to be made manually - the camera is set to whatever the meter says and that's that.
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Jon K. Tormoehlen |
thank you I was stuck on that one! Staci
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Alan N. Marcus |
The objective has always been to photograph an entity and then craft an image so precise that no one can tell the difference. Logic would tell you that to achieve this goal, camera exposure, processing and printing must be exact. Imaging science created measuring tools. Over time, the center of the gray scale range of negative film was found to be about 0.75 units of transmitted density. The center scale of print paper was adjusted to 0.75 units of reflected density. Thus if a medium gray target with a reflected density of 0.75 is photographed correctly, the resulting negative and print will all exactly match the original Such an object turns out to be a target with a shade of gray that reflects 18% of the ambient light. Thus reflection light meters were adjusted to set camera exposure so as to produce middle gray on the film. To achieve correct exposure the object metered must be an 18% target. Not practical unless the photographer carries one and places it in the scene and exclusively measures it. Without the grayscale target meter reading skill must be acquired. Weighted meter readings are one answer. The Incident meter solves the problem as it measures light just about to fall on the subject. The logic of the incident meter is that it produces a reading that is exactly the same as a reflected light meter reading an18% gray target. The incident method is often the most accurate and is favored by motion picture photographers.
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
must be the phd. version
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