This may be most common use of shutter priority by new users. As you increase the shutter speed, motion blur is diminished until it can be stopped in all but the most extreme cases. When taking a picture, most people think “Blur is bad; sharp is good.” Later in this discussion we hope to change your minds about this, but for now, let’s consider how to remove motion blur. Most cameras will allow you to set a shutter speed of up to 1/2000 sec. and some will go as high as 1/8000 sec! One problem you will encounter is that the faster the shutter speed, the more light you require. This means either using a wider (i.e., smaller numbered) aperture and/or increasing your ISO setting. Also, your camera will increase your aperture to the maximum (smallest number) value which will limit your depth of field. You can increase your ISO, but this will introduce more noise into the photo as you increase the ISO level. The only other option is to find a subject that has better lighting – either natural or artificial. For this reason, you will likely want to use the slowest shutter speed that you can get away with to acceptably freeze the action. This will depend on a variety of factors: The speed of the objects in your scene, whether they are moving across the scene or more towards or away from you; how large a portion of the frame they take up and, to a lesser extent, how large your resolution is.
The key point is this: How far will their image travel across your frame during the period when the image is being exposed? Large (in the frame) subjects moving quickly directly across your frame in a high-resolution photo will require a faster shutter speed so that they do not shift their position to new pixels in your sensor during the exposure. Subjects moving towards or away from you or moving slowly will be easier to freeze in place with a slower shutter speed. Likewise, if you are capturing a lower resolution image, the effective pixels are larger which requires the image to move further before encroaching on different pixels on the sensor.
Because the aperture will automatically be increased (become a lower number) which reduces the depth of field, using shutter priority to get a faster shutter speed is ironically often not the best way to go – you are better of using manual mode. The case where it is fully appropriate to use shutter priority to freeze action is in fast moving environments where you don’t mind – or even welcome – a shallow depth of field. This occurs most often when shooting sports events.
- Put a sprinkler or hand-held sprayer in direct sunlight. Experiment with various shutter speeds to see what it takes to freeze the water droplets.
- Find a flying bird – in direct sunlight if possible. Try various exposures to freeze the motion of the bird and even freeze the flapping of its wings. If you really want a challenge, find a hummingbird and see if you can freeze the motion of its wings (hint: think at least 1/1000 sec)!
- With the camera on a tripod, pre-focus on an object placed in the center of the container, then change to manual focus to lock-in the focus setting. Drop an object into the center of the container and see how the splash changes as you change the shutter speed. Try this with strawberries or cherries in a large glass and focus just under the waterline for a great shot!