Previously, the concept of the Exposure Triangle was introduced as an effective framework for moving beyond Auto Mode and exploring manual exposure adjustments. The three primary components subject to adjustment are ISO, aperture, and shutter speed. Having discussed ISO adjustments, this section will now focus on shutter speed.
What is Shutter Speed?
At its core, shutter speed refers to the duration for which the camera's shutter remains open. In film photography, this represented the amount of time that the film was exposed to the scene. In digital photography, shutter speed is the period during which the image sensor records the scene.
To clarify this fundamental concept for digital camera users, consider the following important points:
Shutter speed is measured in seconds, most often in fractions of a second. A larger denominator indicates a faster shutter speed (for example, 1/1000 is faster than 1/30).
Generally, shutter speeds of 1/60th of a second or faster are recommended. Slower speeds can result in camera shake, leading to blurred images.
For shutter speeds slower than 1/60th of a second, it is advisable to use a tripod or image stabilization technology, which is increasingly available in modern cameras.
Camera shutter speed options usually double with each increment. Common available settings are 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, and so on. This doubling mirrors aperture settings, which also modify the amount of light by factors of two. Therefore, increasing shutter speed by one stop and decreasing aperture by one stop typically maintains the same exposure—this interplay will be elaborated upon in future discussions.
Many cameras provide options for very slow shutter speeds, measured in full seconds (such as 1 second, 10 seconds, or 30 seconds). These settings are useful in low-light conditions, when seeking creative effects, or capturing significant movement. Certain models offer a 'B' (Bulb) mode, allowing the shutter to stay open as long as the button is depressed.
Selecting the Appropriate Shutter Speed
When selecting shutter speed, consider subject movement. The speed of your subject and your creative intentions are crucial.
To freeze motion, opt for a faster shutter speed. If you want to introduce motion blur, select a slower setting. The ideal choice depends on how fast your subject is moving and the effect you want to achieve.
Incorporating motion blur can enhance certain images. For example, slower shutter speeds can be used to depict flowing water, speeding vehicles, or star trails. However, using a tripod is essential in such cases to prevent unintentional camera movement, which is distinct from the intentional blur created by moving subjects.
Shutter Speed – Bringing it Together
Shutter speed should not be considered in isolation from aperture and ISO—the other components of the Exposure Triangle. Adjusting shutter speed typically requires compensatory changes to one or both elements.
For example, increasing shutter speed by one stop (such as from 1/125th to 1/250th) halves the amount of light reaching the sensor. To maintain proper exposure, you may need to open the aperture by one stop (for example, from f/16 to f/11) or increase the ISO (for instance, from ISO 100 to ISO 400).