When you take your photographs, good lighting should be a priority. This is because bad lighting will obscure the photo’s subjects and composition, leaving little to be appreciated. 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. That’s why the camera should be set to collect the correct amount of light.
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.
Low lighting conditions require high exposures to allow more light into the sensor, brightening up the final photograph. Otherwise, the photograph will be underexposed, having too many dark areas, the dark objects loosing their details, and the bright objects becoming dull. 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 determines how long the sensor will be exposed to light. Slow shutter speed means more exposure, while fast speed will allow less exposure. 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. At high speeds, the camera will collect light faster and will amplify the sensitivity of the sensor, but will add noise to the photo.
When manually setting the exposure, the photographer usually sets the aperture and the shutter speed independently. As for automatic exposure settings, the camera will determine the degree of exposure needed according to the light metering technique 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.
In case of extreme lighting conditions, it will be difficult to all cameras (including DSLRs) to get acceptable exposure for all shadows and highlights. High Dynamic Range (HDR?) photography, which employs capturing the same photograph at different exposures, is used in this case to solve this problem.
A good approach to learn more about exposure is to look at the exposure settings of your previous photographs, and compare 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. As a result, you will get a clearer idea on how exposure can impact your photos.
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