Tutorial #1: Aperture and Shutter

This is a fundamental tutorial on exposure, and the relationship between your camera shutter and aperture. Both elements control the amount of light that reaches the film plane (or digital sensor), but each serve a unique purpose. Let us relate this to the human eye.

Your camera shutter is like your eye-lid, it opens and closes. The time between your blinks, or the amount of time your eye is open is your “shutter speed”. The aperture of your camera is like your eye’s iris. It contracts and expands in relation to how bright the scene is. Now we all remember going into the bathroom as children, and turning the lights on and off and watching our iris expand and contract. This is the same function of your aperture.

Your shutter and aperture each have their own values, each are different. Your shutter values are expressed in terms of seconds. Your aperture values are expressed in terms of “f-stops”. This term, “stops” in photography refers to a change in illumination, whether the change in shutter or aperture. See the chart below for example shutter speeds and aperture f-stops.

The smaller the f-stop number, the larger the aperture diameter will be. In contrast, the larger your f-stop number is, the smaller your aperture diameter will be. So the larger the aperture diameter is, the more light that reaches the sensor. The same goes for your shutter speed. The shorter the shutter duration (in seconds), a smaller amount of light will reach the sensor. The longer the shutter duration . . . OK you get the picture.

Even though each controls the amount of light that reaches the film plane (or digital sensor), the aperture also controls the photograph’s Depth of Field, or the parts of the photograph that are in focus or blurred out. Here’s an example of how the aperture alone will affect the final image. Starting at f/1.4, the subsequent images show their aperture value, and the number of stop changes between it and the original f/1.4.

Notice how the larger aperture (smaller f number) creates more background blur, and the smaller aperture brings things into focus? That is the unique characteristic of your aperture.

So the next time you are out photographing, play around with your settings. You can change your aperture or shutter settings if your camera has a Manual (M) mode, an Aperture Priority (Av) mode, or a Shutter Priority (Tv) mode. Consult your camera manual to find out if your camera has these features.

If you have questions regarding this tutorial, please email me at info@spencerboerup.com for questions. Thanks again for tuning in to my tutorials!