Photography Exposure Basics

Photography Basics

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Exposure is the amount of light collected through the sensor in your camera during a single photo.  If the shot is exposed too long, the photograph will appear washed out.  If the shot is exposed too short, the photograph will be too dark.  Nearly all cameras nowadays have light meters which measure the light in the given shot and set an optimal exposure automatically.

Most people rely on the light meter (which is great), but if you already know how to control your exposures, you could get a few creative and sometimes better images.

The two primary controls for exposure are shutter speed (the amount of time the sensor is exposed to light) and aperture (the size of the lens opening that lets light into the digital camera).  Shutter speeds are commonly measured in fractions of a second.  Apertures are measured in something known as f/stops.

You might wonder why there isn’t only a constant shutter speed or a constant aperture so you might just have to worry about one control.  The reason is that despite the fact that they both manage the amount of light reaching the sensor they also control other factors of the image.  A fast shutter speed, for instance, can be used to freeze subjects, and a slow speed can be used to blur the water.

Aperture controls the depth-of-field which is what is in focus in the image.  A wide aperture can blur the background and therefore draw interest to one subject. Aperture can also be used to focus everything in a photograph with a narrow aperture.

On most DLSR cameras today you may even change the sensitivity of the sensor when collecting light that is known as the ISO speed.  The typical span of ISO speed is 100 to 800.  The higher the ISO speed, the quicker the camera collects light, however, it also adds more significant noise to the picture than the lower speeds.

For instance, if you’re trying to snap a shot in dim light without a tripod you may want to increase the ISO speed for you to get an image that’s not blurry.  Most of the time you need to keep it at a lower ISO speed if there is sufficient light, but it makes a huge difference while there isn’t.

The exceptional way to discover ways to use shutter velocity and aperture is to keep experimenting with them.

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