Exposure: Let the Light Shine in

Whether creating a glossy print or a digital JPEG, photography is still all about capturing light. Check out Groupon’s examination of exposure to explore one tool for getting the perfect image.

As complex as it seems, photography is a simple phenomenon requiring only light-sensitive material inside a dark box and a hole with a shutter. As the shutter opens, light streams through the lens, exposing a piece of film or an SLR's digital sensor to the image outside the box. Thanks to that exposure, the once-fleeting light becomes a photograph, rendered in precise detail and preserved for all posterity.

The exact exposure depends on the shutter speed, which can last as short as 1/2500th of a second to as long as several hours. A faster shutter speed captures faster action but requires more light and therefore a larger opening—or aperture—which shortens the field of focus. Conversely, a slower shutter speed needs a much smaller aperture to capture the same amount of light, though this also exposes the camera to the image for a longer time, making the stars look like lines drawn across the sky or a waterfall look like a solid white curtain draped from a giant's towel rack. Of course, a proper exposure is a matter of balance—too much time in bright light, and the photograph will wash out. Not enough time in the darkness, and the world will be nothing but shadows.