Each camera has a shutter that allows light to shine on the image sensor for a set period of time. The default position for the shutter is to be closed, and it will be opened only for a set period of time. The period of time the shutter is open is measured in seconds or fractions of seconds.
Sharpness and shutter speed
When using slower shutter speeds, the shutter will be open longer exposing the image sensor to light for a longer period of time. While the shutter is open, any movement of the camera or subject will be recorded on the image sensor as a blurred image. Sometimes this is a good thing, sometimes this can be a bad thing.
Motion blur can be used to give a sense of motion to the subject. A fast-moving arm from a pitcher might appear blurred showing the movement of the arm. A runner photographed with her legs in motion and thus, only slightly blurred will give the viewer the indication of motion.
Sometimes a slow shutter speed will be used solely to increase the amount of light gathered in a low-light situation. When photographing at night, longer shutter speeds might be used in order to gather enough light for proper exposure. Sometimes the longer exposure might be used to gather enough light in a low-light environment as well as motion blur to convey movement.
Conversely, fast shutter speeds might be used to freeze movement of fast-moving subjects. A batter swinging at a ball would need a fast shutter speed to properly freeze motion. Catching a photo of a bird in flight will need a fast shutter speed to freeze the bird and have a sharp image.
Another reason for a fast shutter speed is to have proper exposure in very bright conditions. Taking photographs outdoors on a well-lit day with few clouds might require very fast shutter speeds. In some instances, being outside on a well-lit day with no clouds and a light-colored subject or background might be beyond the shutter capabilities of some cameras!
How is shutter speed measured?
Shutter speed is measured in seconds and fractions of seconds. Typically, a shutter speed of one second would be shown as 1” or 1s on most cameras. The quotation mark “ or s denotes that the measurement is in seconds. At shutter speeds below one second, the speed will be a fraction such as 1/250 or 1/500.
Every camera will have a range of speeds that the shutter can attain. Some will have speeds as slow as 30” and some will even have a BULB mode that can hold the shutter open indefinitely. BULB mode is useful for taking photos in very low-light situations and in astrophotography.
On the other end of shutter speed is the fastest attainable shutter speed. Most consumer cameras and professional photo cameras will get to somewhere between 1/4000 of a second and 1/8000 of a second. That is for normal, photographic cameras. There are some high-speed specialty cameras that shoot much, much higher for extreme purposes.
Shutter speed and the exposure triangle.
You will notice as you look at a chart of shutter speeds, that there is a pattern that emerges. Let us look at a standard shutter speed of one-quarter second or 1/4. The next full step from 1/4 is 1/2 or one-half second. It is easy to visualize that if the shutter is open for one-half, it lets in exactly twice as much light as a shutter that was open for one-quarter second. Conversely, a shutter that was opened for 1/2 second would let in exactly one-half the light of a one-second exposure.
These steps are called stops of light or f-stops. There are similar f-stops of light that can be adjusted for with the camera’s ISO and aperture. The unity of all three of these parts of the exposure triangle results in a properly exposed photographic image.
Fast versus slow shutter speed.
Now let us discuss slow and fast shutter speeds in particular.
Slow shutter speeds
Slow shutter speeds are those shutter speeds of one second and longer (totally my own determination). At one-second and above you will need to employ a tripod or some other means to steady the camera. At these long shutter speeds, it becomes impossible to hand-hold a camera steady enough to not introduce camera shake into the image. Camera shake will manifest itself as a blurry image, versus a sharp image. Note: a slow shutter speed by itself does not necessarily cause an image to lose sharpness. If the camera doesn’t move and the subject being photographed doesn’t move, the image can be sharp.
When used for low-light photography, the slow shutter speed allows more of the available light to enter the lens and strike the image sensor. It simply allows more photons of light to enter the lens and hit the image sensor. The longer the shutter is held open, the brighter the resulting image will be.
Fast shutter speeds
Fast shutter speeds are those shutter speeds below one second. Fast shutter speeds are used to freeze action in moving subjects. To photograph my daughter pitching a softball during a game, I use 1/500 of a second in order to freeze most of the scene. I say most of the scene because of the speed of her pitching, her hand and part of her arm will be slightly blurred. This conveys motion in the image.
To completely stop motion, I could use a faster shutter speed. A shutter speed of 1/2000 should effectively stop motion. A slide into third base would be frozen at 1/2000 of a second. That is not to say that to stop motion the photographer should just slam the shutter speed to the fastest allowed. That might cause the need for an aperture that is too wide or an ISO that is too high.
Creatively, I try to use a shutter speed that is slow enough to give me creative choices with my aperture and ISO, but fast enough to have the desired effect (blur or freeze) on the image I am trying to create.
At the end of the day, the shutter speed you select for your photograph impacts whether the image is frozen or if motion blur is allowed. It impacts the settings of the other two sides of the exposure triangle (ISO and aperture) and it also determines if you will need additional equipment such as a tripod.
Use your shutter speed selection creatively. Not every photo of a subject in motion needs to have motion blur, nor does it always have to freeze a moment in time. Perhaps try something completely different such as freeze the main subject in motion with the background blurred, much as car magazines do with cars in motion.
As you continue through your photography journey and gain more experience, you will come to know what shutter speeds will work best for whatever photographic composition you are working on. Experiment and see what you like to do the most and you will develop your own style.
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