Shutter speeds often control the look and emotion of an image. A fast shutter speed freezes fast-moving subjects, while a slow shutter speed blurs motion to create movement within a single photograph.
In low-light situations, shutter speeds are an integral part of any sharp image. Slow shutter speeds, below 1/30 of a second, require either image stabilization or a tripod to keep images tack sharp.
The key to using shutter priority mode to produce successful images is to not only understand shutter speeds, aperture, and exposure compensation, but to use them effectively and quickly.
Understanding and Selecting Shutter Speeds
On the camera, shutter speeds are represented by a single number. Ranging from several seconds to 1/8000th of a second, the camera displays only the fraction’s denominator (the bottom number of a fraction) for shutters faster than one second. A typical range of shutter speeds will appear as follows: 2”, 1”, 2, 4, 8, 15, 30, 60, 125, 250, 500, etc. Fast shutter speeds require larger apertures, shown by small f/stop numbers, while a slow shutter requires a smaller aperture, represented by large f/stop numbers.
Similar to aperture priority mode, which controls both depth of field and the quantity of light reaching the sensor, shutter priority mode also control two aspects of every photograph: sharpness and motion.
Sharpness is, perhaps, the most important aspect of photography. The term sharp describes an image, or part of an image, that shows crisp, precise details. By rule, the faster the shutter speed, the sharper the image. Images shot at slow shutter speeds often require image stabilization or a tripod to reduce a loss in sharpness.
Motion can be purposefully frozen or blurred to create dynamic images. When photographing a sporting event, like basketball, fast shutter speeds are required to freeze the motion, while naturally limiting the depth of field by using a large aperture. If shooting in nature, slow shutter speeds are used to blur moving water or swaying foliage, while subsequently increasing the depth of field throughout the entire image.
Exposure Compensation Control
When shooting in shutter priority mode, the camera sets the aperture to match the selected shutter speed. These automatic exposures are often accurate, and allow the photographer to focus on freezing or blurring motion with the shutter speed; however, these exposures can sometimes over or under expose the subject. Unfortunately, any exposure compensation in shutter priority will also affect the image’s depth of field.
The exposure compensation, represented by the +/- symbols, allows the photographer to purposefully brighten or darken any image without sacrificing their pre-selected shutter speed. Unlike manual mode, where the photographer must adjust the aperture correctly, exposure compensation is a simple plus or minus scale. Setting the camera at +1 increases the aperture by one stop, therefore brightening the image and reducing the depth of field. Setting the camera at -1 would darken the image, while increasing the depth of field.
Common examples that require exposure compensation are photographs taken on snow or sand. These bright surfaces are often underexposed by the camera, so dialing the exposure compensation to +1 or +1.5 will produce more accurate exposures, but lower the depth of field in the photograph. Athletes in a dimly lit gym are often overexposed, requiring an exposure compensation of -1 or -1.5. While this setting will properly expose the dark environment, keep in mind that the depth of field behind the subject will increase.
Six Steps to Properly Exposed Images Using Shutter Priority Mode
- Set the camera to shutter priority mode and compose the image.
- Choose a shutter speed to suit the subject. Use a tripod and slow shutter speeds to blur motion or freeze action with fast shutter speeds.
- Determine if the automatic aperture is adequate. Will the depth of field be too shallow or too deep?
- Estimate the brightness of the scene. Overly dark or bright scenes often require manual exposure compensation. Keep in mind this will affect the depth of field.
- Take the shot and verify the results on the camera’s LCD screen.
- Make required adjustments, and retake the shot.
Jeff Bartlett - I still fear the all–too–common travel situation that seems to arise at least once per week. The one where I am sitting in a ...
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