Friday, July 13, 2012

Exposure in Photography

    What photographers do is capture light; understanding light and capturing it is key to creating amazing images.

    To capture light you need a medium in which the light captured is exposed unto; it was film during the SLR days. With the advent of DSLRs, light is exposed unto digital sensors called CCD or CMOS depending on the technology your digital camera is using.

    Three things are used in combination to get exposure: film speed(ISO), aperture, and shutter speed. In my own opinion, the most important of the three are aperture and shutter speed. Learning to capture images in full manual will help you understand why. Knowledge of how ISO works in conjunction with aperture and shutter speed will aid you with studio lighting work or situations in which you are adding to ambient light.

    Shutter speed and aperture directly control how much light is let unto the sensor or film. Aperture is measured in units called f numbers and affects the lens opening and the amount of light let in; it directly affects depth of field. Shutter speed controls the amount of time light is allowed to be exposed unto the film or sensor. Film speed(ISO) is the sensitivity of the sensor or film to the light exposed onto it. The higher the ISO the higher the film/sensor sensitivity. High ISO is usually used in low available light situations or situations in which higher shutter speeds is needed.

    Finally, a good light meter is needed to determine the correct combination of aperture, shutter speed and ISO setting needed to get accurate exposure.

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