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When an optimal amount of light strikes the film, the resulting image is one that faithfully reproduces the subject. This optimal amount of light is called a "standard exposure," and reproduces the subject using details and tones close to those seen with the naked eye. In principle, a "standard exposure" is the exposure value that reproduces an area of an image with a reflective ratio of 18% as 18% on the film. A camera's built-in exposure meter and auto exposure (AE) operate based on this "standard exposure."

Standard Exposure and Under/Overexposure


[ Underexposure ] Insufficient light makes the entire image dark. Detail has turned to black and tone is lost.		[ Standard exposure ] With the optimal amount of light, the subject is reproduced with the same detail and tone as seen with the naked eye.		[ Overexposure ] Too much light makes the entire image whitish. Detail and tone have been blown out.

This shade of gray has a reflective ratio of 18%.

One basic point of successful photography is that gray with an 18% reflective ratio in the subject's dark and light areas should be correctly captured as the same 18% on film. The exposure value used in this case is called the "standard exposure."

	Why is the reflective ratio 18%? One reason is that the reflective ratio for human skin is approximately 18%. Since many of the pictures we take are of people, an exposure that can accurately reproduce the color of human skin is used as the "standard exposure."
	Why is the reflective ratio 18%? Because the average reflective ratio for subjects (e.g., for scenery) we see in our daily lives is regarded as approximately 18%. Therefore, the exposure that faithfully reproduces these ordinary scenes is used as the "standard exposure."

	This shade of gray has a reflective ratio of 18%. 18% gray reflectors are sold in camera stores as the standard light reflectors. If 18% gray can be faithfully reproduced, both the light and shade sections of the subject can also be reproduced. The reflective ratio for the back of your hand, a blue sky or a green tree is approximately 18%.When you have trouble determining the correct reflective ratio, the ratio of these subjects can be used for reference.

Is "optimal exposure" different from "standard exposure"? ?Each photographer has an "optimal exposure" that matches his or her perception.

In photography, the word "optimal exposure" is similar to "standard exposure." "Optimal exposure" refers to the exposure that will express the photographer's preconceived image in the resulting photograph. As an extreme example, if the photographer's image is a completely black photo or a photo that is completely white, the exposure will be "optimal" if the photo is taken exactly as the photographer intends it ? totally black or totally white. In other words, a subject always has only one "standard exposure," but there are an endless number of "optimal exposures" that express the photographer's intended image.


Underexposure can be used intentionally to emphasize, for example, the weight and solidity of a metallic object.	Overexposure can be used intentionally to express a bright light or the beautiful transparency of a young woman's skin.	Intentional extreme underexposure will emphasize the mechanical beauty of a motorcycle, which has the effect of turning unnecessary sections of the image black.