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Shutter Speed & Shutter Priority Mode

What is Shutter Speed?

Your camera's shutter mechanism allows light to enter the camera lens and onto the digital sensor or film, for a specific length of time. Controlling the shutter speed allows you to control the effects of motion in your photographs. Fast shutter speeds gives you the ability to freeze motion or action in your photo while a slow shutter speed produces blur in your images that would denote motion or action in your photograph.

How do we measure Shutter Speed?

Shutter speed is measured in seconds or fractions of a second shown below in full stop increments. Note that some newer cameras allow for partial stops like 1/3 or 1/2 stop increments. For simplicity's sake, I will show you full stop increments in this article.

8 secs, 4 secs, 2 secs, 1 sec, 1/2 sec, 1/4 sec, 1/8 sec, 1/15 sec, 1/30 sec, 1/60 sec, 1/125 sec, 1/250 sec, 1/500 sec, 1/1000 sec, 1/2000 sec, 1/4000 sec, 1/8000 sec

Figure 1 below shows different images taken using different shutter speeds with the aperture and ISO values remaining unchanged to isolate and show the effect of shutter speed on the exposure of a photograph.

Shutter Speed Effects
Figure 1: Effects of Shutter Speed on Exposure

In the example image above, I used shutter speed 1/15 sec, aperture F/4 and ISO 1600 to get the optimal exposure shown in the middle image. The images on the left of that, I used a slower shutter speed which added more time for the light to enter the lens and hit the sensor. This had the effect of overexposing the image. The images on the right, I used a faster shutter speed thus limiting the length of time that the light entered the lens and hitting the sensor. So, the opposite effect happened - underexpose of the image.

Capturing Motion with Shutter Speed

In the Aperture & Aperture Priority Mode, the article discussed a creative effect of aperture on your photograph which is Depth of Field. Shutter Speed also has a creative effect on a photograph which is capturing action or motion in your photo.

As stated above, controlling the shutter speed allows you to either capture a moment in time (freeze motion) or denote motion in your photograph by allowing blur in your photo. Fast shutter speed freezes action while slow shutter speed produces blur which conveys a sense of motion in your photo.

A side by side example image is shown below showing a comparison between fast and slow shutter speed.

Shutter Speed and Motion Blur
FIGURE 2: Conveying motion using Shutter Speed

The subject on the photos above is a spinning globe. In the left half of the image, I wanted to convey motion and show my intended audience that the globe was spinning. In this case, I chose a slow shutter speed of 1/60 second. In the right half of the image, I wanted to capture a split second of the action rendering the spinning globe frozen in time. In this case, I used a fast shutter speed of 1/1000 second which virtually eliminated the sense of motion in the photo.

The dreaded Camera Shake!

Sometimes when holding a camera by hand and taking a photo, you will get blurry photos when you don't intend to. This is caused by a phenomenon called Camera Shake. Camera shake is caused by movement at the time when the shutter is open and the photo is taken. This can be avoided by following a general rule in photography. When hand holding a camera, the shutter speed must be equal or faster than the numerical equivalent of "1/focal length" of your lens. For example, a 60mm lens should be hand-held with shutter speed that is not lower than 1/60 sec. So, longer the focal lengths have higher probability of camera shake. For example, a 200mm lens will not allow you to hand-hold a camera any lower than 1/200 of a second! Unless you are a robot, I would recommend you use a tripod.

Shutter Priority Mode

Shutter Priority Mode Dials

There are situations where the photography would opt for using the Shutter Priority mode over the Aperture Priority mode. Taking action shots is one of these instances. Action opportunities like sports (basketball, soccer, etc) or just kids running around. In this case, you can use Shutter Priority mode to freeze the action or blur it depending on your creative needs. Another instance is if you have limited lighting like at night for example. In this case, you can use longer shutter speeds to allow more time for the light to hit the sensor for a good exposure.

Shutter Priority Mode is a semi-automatic setting on your camera that gives you the ability to select the shutter speed value while the camera automatically selects an appropriate aperture to come up with an optimal exposure.

To set your camera to Shutter Priority Mode, look for an Tv (Time Value) or an S (Shutter) symbol on your camera dial. Different camera manufacturers may use another symbol so read your camera's product manual to figure out how to set Shutter Priority Mode on your camera.

Try this experiment!
It's time to tinker with your camera! This time, take a few minutes to figure out the Shutter Priority Mode setting on your camera. Become familiar with it and then set your camera to Aperture Priority Mode.
Consult your manual if you do not know how.

What to watch our for when using Shutter Priority Mode

When using Shutter Priority Mode, you need to be aware not to underexpose your photograph. It is easy to do this just by picking a shutter speed that is too fast for the available light where it may require an aperture that is greater than the maximum opening of your lens. Pay close attention to your exposure display as it would tell you if your settings are too low for the available light of your scene. On my Nikon camera, the exposure display show Lo to indicate that you will likely get a low or underexposed image. One solution to this problem is to bump up your ISO setting to allow more sensitivity to light. Most DSLR cameras allow for maximum ISO setting of 1600 or above.

Low Exposure Display
Figure 3: Low Exposure Display

Similarly, you can also run the risk of overexposing your photograph. If you pick a shutter speed that is too slow where your lens' minimum aperture is not small enough to restrict the excess light from hitting your image sensor. Again, pay attention to your exposure display screen. On my Nikon camera, the exposure display will show Hi to indicate that the image will likely be overexposed. One solution to this problem is to set your ISO setting down to its lowest setting. Most DSLR cameras have minimum ISO settings of 200 or less.

High Exposure Display
Figure 4: High Exposure Display
Related Topics
  1. Online Course #1: Understanding Exposure
  2. Aperture & Aperture Priority Mode
  3. What is ISO?