:: photo tips :: understanding exposure

September 30, 2013

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Understanding Exposure

photo tips :: september 2013

The hustle and bustle of summer has finally come to a close. Kids are back in school and I’m gearing up for busy fall season. I skipped my August newsletter to focus on design projects, but previous photo tips can always be viewed on my blog.

Like other creative mediums, photography is about telling a story. You have to have something you want to say or something you want to express. Your camera is the tool that you use to express it. There are three settings on your camera that will affect the exposure. They are called Aperature, Shutter Speed, and ISO.

Exposure = Aperture (amount of light made available to record an image) + Shutter Speed (the length of time the light is made available to record an image) + ISO (sensitivity to light).


Aperature

Aperture is an adjustable circular opening by which light enters a camera, through a lens, to record an image. The size of the opening is the aperture, and when you control the aperture you determine how large or small the hole is. Aperture is measured in f-stops, such as f/22 and f/4, but here’s the thing: The smaller the f-stop number, the larger the opening, and vice versa.


ISO

ISO (International Standards Organization) is the sensitivity to light of the sensor. The higher the sensitivity, the less time (shutter speed) or the less amount of light (aperture) needs to hit the sensor for the correct exposure. We use ISO to help us achieve what we want to do with the other two sides of exposure; Aperture and Shutter Speed. Why don’t we just use the most sensitive one and forget about it? Because the downside of higher ISO is that it increases the grain in our images. So our objective is to use the lowest ISO possible, but balancing that to what we want to achieve. For example of light sensitivity, think of staring straight into the water while on a sunny beach or squinting at a clock in a semi-dark room. Now imagine your camera trying to capture images under those conditions.


Shutter Speed

The shutter speed controls how long the light comes through our aperture to the digital sensor. The longer the time, the more light will hit their surface. That is technically what shutter speed does. Think of actual window shutters in your home, and how quickly or slowly you open and shut them: the longer you leave them open, the more light enters your room. Shutter speeds are expressed in fraction of a second (1/8, 1/125, 1/1000 etc.).

NOTE:: If you are using a very slow shutter speed (like image above), make sure your camera is stabilized on a tripod or non-moving surface to prevent camera shake.


Creating the perfect exposure

Shooting in manual mode to master your exposure settings can be frustrating––a change to one (aperture, shutter speed, ISO) will impact the other two. Keep practicing and remember the following rules: If your pictures are too bright, try increasing your shutter speed, upping your aperture (higher number, smaller hole), and/or reducing your ISO. Conversely, if your pictures are too dark, decrease your shutter speed, reduce the aperture, and/or increase your ISO.

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