Isle of Man Mansions

Tuesday, 2 February 2010

Overexposure and underexposure

A photograph may be described as overexposed when it has a loss of highlight detail, that is, when the bright parts of an image are effectively all white, known as blown out highlights (or clipped whites). A photograph may be described as underexposed when it has a loss of shadow detail, that is, the dark areas indistinguishable from black, known as blocked up shadows (or sometimes crushed shadows, crushed blacks, or clipped blacks, especially in video).As the image to the right shows, these terms are technical ones rather than artistic judgments; an overexposed or underexposed image may be "correct", in that it provides the effect that the photographer intended.
isle of man luxury villa

exposure value

In photography, exposure value (EV) denotes all combinations of camera shutter speed and relative aperture that give the same exposure. The concept was developed in Germany in the 1950s, in an attempt to simplify choosing among combinations of equivalent camera settings. Exposure value also is used to indicate an interval on the photographic exposure scale, with 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a “stop”.

Exposure value was originally indicated by the quantity symbol $E v$ ; this symbol continues to be used in ISO standards, but the acronym EV is now more common elsewhere.

Although all camera settings with the same exposure value nominally give the same exposure, they do not necessarily give the same picture. The exposure time (“shutter speed”) determines the amount of motion blur, as illustrated by the two images at the right, and the relative aperture determines the depth of field.

H = Et

H is Photometric Exposure

E is Image Plane illuminance

t is Exposure time

isle of man mansions

The Theory of Exposure

isle of man mansions
Difference in one f stop is different to one f stop in shutter speed then

Single Light Studio Portrait Photography : White Cards in Single Light Studio Photography

isle of man mansions

Monday, 1 February 2010

Photometry

Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy (including light) in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by a luminosity function (a.k.a. visual sensitivity function) that models human brightness sensitivity. Typically, this weighting function is the photopic sensitivity function, although the scotopic function—and others—may also be applied in the same way.
http://isleofmanmansions.blogspot.com/