Basic Exposure Techniques

Posted on | August 17, 2009 | No Comments

 

When you take your photographs, good lighting should be a priority. No matter how good is your composition, if the lighting is not good, then the whole photo will not be good either. It has this power to ruin a good image and make it useless, but it also has the power to make an ordinary photo, a great work of art. Learning how to capture the correct amount of light is an essential part of photography.

During the capture of a single photograph, the photographic medium (film or digital sensor) is allowed to gather a certain amount of light indicated by its exposure. There is no fixed value of a correct amount of light, because it depends on the available lights, the objects, and the photographer’s judgment. However, it is safe to say that there’s an acceptable exposure and an unacceptable exposure. Unaccepted exposures are, in general, due to a mistake rather than a photographer’s intention.

Basically, a dark scene will need long exposures, allowing more light to be collected by the sensor, which translates to a well exposed photograph. If less exposure is used, the photograph will become darker as a result of the underexposure. Alternatively, a bright scene will need short exposures, limiting the amount of light collected by the sensor, yielding a well exposed photograph. If more exposure is used, the photograph will become too bright with many blown highlights.

The camera controls the exposure through shutter speed and aperture. Shutter speed controls the time for which the shutter will stay open. The faster the shutter speed is, the less light will get to the sensor. On the other hand, aperture controls the degree of openness of the lens. Narrow aperture will let less light pass through it than a wide aperture. ISO speeds also affect the degree of exposure. Higher ISO speeds will make the sensor more sensitive to light, reducing exposure, but it will add undesired noise to the photos.

In manual exposure mode, aperture and shutter speed are usually set independently. When automatic exposure is used instead, the camera will calculate the optimum exposure based on the light meter used. Because of the lack of manual controls over exposure in many low-end cameras (including most digital compact cameras), exposure compensation (if available) should be used to fine tune the automatic exposure suggested.

Photographs with very dark and very bright spots will not show correct exposure on all their parts using any type of cameras. Usually, photographers take the same photograph at different exposures, and combine them together using software programs.

To understand exposure better, try to study your photographs through viewing them and the settings you used when you took them. Look for the exposure time (shutter speed), the aperture, the ISO speed, and the exposure compensation in the data that is stored in your image files. This is the best way to understand these things practically.

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