Digital Photography for Beginners: Start HERE – What is Exposure?

Exposure.   Exposure is the essence of photography and digital photography and in my opinion, is the unifying concept in digital photography.  Now this may sound like quite a proclamation to make, but I didn’t really start to understand anything about digital photography until I really understood the concept of exposure.  Note carefully as I said the “concept” of exposure.  Exposure is a straightforward concept to understand, but in practice it’s an art that like any other creative endeavor, is a difficult one to master.

What is Exposure?

Put simply, exposure is the amount of light that your camera will use to take a digital photograph, and this “amount” is usually set by your camera automatically.  Taking this definition a step forward, when you go to take a picture, your camera automatically meters the scene and picks what it thinks a good amount of light would be needed to take the shot.  Remember, the camera can’t know what you want out of a picture, but if you are outside taking a shot of some flowers in your yard, and you press the shutter button down halfway, the camera will guess as to what level of light it thinks will make for a good image.  This amount of light is what’s called the exposure.  So to recap, the digital camera automatically meters (checks the amount of light in the scene), and then picks an exposure level that it thinks is appropriate.

Aperture, Shutter Speed, and ISO

A lot of things go into the next step, that is, when you depress the shutter button and a picture is taken.  Of the things that occur, the considerations of aperture, shutter speed, and your ISO settings are paramount.  I will talk about these three variables in the coming articles, but here is the key take-home concept:

Aperture, shutter speed, and ISO all contribute to the controlling amount of light that enters your camera, and thus brings you to the proper amount of light to get to your determined exposure.   You will learn later about the relationship among aperture, shutter speed and ISO, but realize now that the end-point is the metered  level of exposure.  You can vary any of the three settings (aperture, shutter speed, and ISO), but in the end you will still be aiming for this same level of exposure.   Put a different way,  you can think of these three variables as levers, which you can pull up and down in different directions in order to get to your exposure.  These settings do have a relationship, so they do need to be in balance in order to get to the appropriate exposure.

Exposure is an easy concept, but understanding how aperture, shutter speed, and ISO work together to get to you your exposure is a little more tricky. In the next few articles I’ll walk you through each of these variables in turn, and in doing so the pictures of the relationship between these three factors and the exposure will become much more clear.

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