DSLR Camera Basics


“Exposure” is the act of exposing the image sensor to light. By adjusting the amount of light, you can make a photograph of a bright sunlit scene look dark, or a shot of a dark interior look bright. DSLR Cameras have auto-exposure systems that automatically produce photographs of optimal brightness. You can use this system for optimal results with both brightly-lit and poorly-lit subjects. This is referred to as “optimal exposure.”

Photograph taken using auto-exposure

The camera meters the brightness and color of the subject and automatically adjusts exposure for optimal results.

In concrete terms, leaving the camera in charge of exposure produces optimal results with a variety of scenes. Photographers, however, may feel that brighter results would be better for some photographs and that darker results would be better for others, meaning that they may not necessarily find that the optimal exposure selected by the auto-exposure system is suitable for all photographs.

The Same Scene Photographed at Different Exposures

Reducing exposure emphasizes shadows and makes the sky a darker blue.
In this photograph, the camera auto-exposure system has adjusted exposure for optimal results.
Increasing exposure brings out details in shadows, including the road and cars.

Here are some samples of the same scene photographed at different exposures. You may want to reduce exposure to bring out the color of the sky, or increase exposure to bring out cars and other details in shadows. The “best” exposure varies according to photographer and what details he or she considers important or wants to emphasize.