MikeRun, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Shutter speed is the length of time that a camera is open while taking a photo. A slow shutter speed means a brighter photo but an increased likelihood of blur. A fast shutter speed means frozen motion but the photo will be darker. Everyone who’s been doing photography for a reasonable amount of time knows the two ways shutter speed affects a photo: exposure and motion blur. But that’s not all there is to it, here are seven less commonly known ways that shutter speed affects (or doesn’t affect) a photo.
How does shutter speed affect depth of field?
Shutter speed doesn’t directly affect a photo’s depth of field or bokeh. Depth of field is only determined by the distance from a subject, aperture, and focal length. However, it is possible that reducing shutter speed can indirectly increase depth of field and vice versa. This is because most consumer cameras will automatically change settings that do affect depth of field in order to compensate for your manual change in shutter speed. This can be mitigated by switching to manual mode.
Depth of field
That was the short answer, here’s the long one. In order to understand how shutter speed affects DOF, first, we need to know what it really is. Most people simply know depth of field as “the thing that makes blurry backgrounds” (also called bokeh) but how does that work? Depth of field can best be described as the amount of focus beyond the focus point. A large depth of field will make your camera continue its focus far into the background, while a narrow depth of field will stop focusing shortly after the focus point, hence the blurry background. Here’s a neat illustration of how depth of field works.
As stated earlier the three factors that affect depth of field are distance, aperture, and focal length. If a subject is close to the camera, the depth of field will be narrow. Aperture is simple, a larger f stop number means a larger depth of field. Finally, wider focal lengths have a deeper depth of field than zoom lenses. For the purposes of this article, you only need to remember that fast aperture means shallow depth of field.
The exposure triangle refers to the three main settings affecting the overall light in a photo. It consists of aperture, shutter speed, and ISO. If you want a photo to be exposed properly you need to balance these three settings. You can’t go all-in on one setting as each comes with its own limit/drawbacks. Aperture has a physical limit, shutter speed comes with motion blur, and relying on ISO can indirectly cause noise. Many people don’t understand the concept of the exposure triangle, so cameras will balance the exposure settings automatically unless you’re in manual mode. This means when you adjust shutter speed, the aperture will be adjusted to compensate for it. That’s why changing shutter speed can indirectly change the depth of field.
How does shutter speed affect video?
Shutter speed matters just as much in video as it does in photos. It’s a common misconception that at a shutter speed of 1/60 you’ll be recording at 60 frames per second. This is not the case, shutter speed can be set to any amount that doesn’t overlap frames onto each other. So a 30 fps video can have a shutter speed of 1/60 and the shutter will simply not be open for half of the time.
How does shutter speed affect frame rate?
Contrary to popular belief, shutter speed doesn’t affect FPS at all. Many people think a shutter speed of 1/60 must equal 60 FPS. This is not true because the camera can take breaks in between each shutter release. Any shutter speed length can be used in a video as long as it’s not too long.
Many people don’t actually understand the meaning of the words FPS and shutter speed. They are not interchangeable. This comes from an overthinking of how video works, you can think of it the same thing as a burst of photos. (Of course, a rolling electronic shutter is used otherwise the sound would be unbearable.) If a video is taken at 60 fps, it’s like 60 normal photos being taken in a second, the photos can have any shutter speed below 1/60. Although a good rule of thumb is to put the fps in the denominator and double it, so a 24 fps video should have a shutter speed of 1/48. You can go over or under this number depending on how you want your video to look.
Slow vs fast shutter speed
A video with a fast shutter speed will freeze motion in each frame but the video will look more choppy. In a video with a slower shutter speed, each frame will look more blurry but the video will feel smooth overall. Different approaches can be taken depending on how you want your video to feel, but in my personal opinion I’d stick with the doubling the denominator rule, if I had to choose I’d go with the smoother option.
How does shutter speed affect exposure?
A higher shutter speed positively affects the amount of light present in a photo. When shutter speed is longer, more light enters the camera and vice versa. In night sky photos, shutter speeds up to 30 seconds are used to absorb the most light possible. The only thing stopping people from using more is the blur caused by the rotation of the earth.
The other effect of shutter speed to exposure besides the amount of light is motion blur. A faster shutter speed freezes motion while a slower shutter speed can be blurry. As mentioned earlier, shutter speed can also indirectly affect other factors in the exposure triangle like aperture and ISO when not using manual mode. So the effects of increasing shutter speed will increase the effects of aperture and ISO. These include an increased depth of field and increased noise. If you’d rather have a chance of blur over an increased depth of field and noise, then turn up your shutter speed. (Especially when using a tripod as there will be no blur.)
How does shutter speed affect focus and sharpness?
Shutter speed doesn’t affect a photo’s actual focus point but it can affect overall image sharpness. High shutter speeds can cause motion blur and indirectly cause background blur known as bokeh. Although this won’t directly affect focus, it can still cause a photo to look blurred.
I’m defining focus in this context as the focus point. Strictly speaking, shutter speed doesn’t do anything to the focus point at all. So changing it shouldn’t do anything to overall focus right? As mentioned earlier, your camera tries to compensate for any change in shutter speed if you’re not on manual mode. You’ve already guessed it, when you change shutter speed, aperture changes too and as mentioned earlier, aperture affects depth of field.
Depth of field and focus are closely related, remember the graphic from earlier in the article? A shallow depth of field will stop the camera from focusing on objects in the background. This effect is called “bokeh“, this originates from the Japanese word “boke” meaning blur or haze. Usually, it’s aesthetic and done on purpose, but it can be accidental. A decrease in shutter speed leading to an increase in aperture may accidentally trigger a bokeh effect.
Sharpness isn’t a strict photography term like focus. Sharpness simply refers to the overall detail quality of a photo. As you know, increased shutter speed can cause motion blur and this definitely reduces the overall sharpness of a photo. And an unintended bokeh effect doesn’t make your photo look sharp either.
How does shutter speed affect noise?
A longer shutter speed will decrease the amount of visible noise in a photo because more it allows more light to reach the sensor. Noise occurs when one doesn’t have enough actual exposure and tries to compensate for it using ISO. Therefore, ISO doesn’t actually cause noise, but the lack of aperture and shutter speed that comes with relying on it does.
Main causes of noise
First of all, what is noise? Noise is the graininess you can see in low quality or underexposed photos. There are primarily two reasons that noise occurs. The first is the randomness in photon distribution. The second is caused by imperfections in your camera’s sensor. Many people think noise is directly caused by ISO, but in reality, it’s caused by a lack of actual light that usually conceals it. When you try to make up for a lack of light by bumping up the ISO or increasing exposure in photoshop, you amplify noise even more. Instead of using ISO to make a photo brighter, increase the aperture and shutter speed. However, don’t make your shutter speed too long.
Not enough shutter speed can cause noise, but too much of it can as well. The noise caused by the imperfections in your camera sensor is amplified with increased temperature as they heat up with use. So during long exposures, heat in your camera is increased, causing noise. So make sure to find the perfect balance between too little and too much shutter time. There is also an option in most Nikon and Canon cameras called “long exposure noise reduction.” This works by taking two consecutive photos and stacking them on top of each other.
How does shutter speed affect image quality?
If you’re referring to image quality as the resolution of your photo then no, shutter speed doesn’t affect image quality at all. But if you’re referring to the look of the photo in general, it does. Increased shutter speed means a brighter but possibly blurrier photo and vice versa.
Image quality can sometimes mean file format and the resolution of a photo. This is what “image quality” means according to the options menu on of Nikon camera. However, many people don’t consider “image quality” to mean resolution specifically. According to the Encyclopedia of Imaging Science and Technology, image quality is defined as “the weighted combination of all of the visually significant attributes of an image” which shutter speed most certainly affects. A longer shutter speed means more light can enter the camera. This is especially important in night sky photography. In fact, shutter speed is so important to the quality of astrophotography that you can buy machines to turn your camera with the rotation of the earth, so photographers can take longer exposures that are usually impossible without star trails. In sports photography, shutter speed freezes motion which is very necessary when photographing fast-moving objects.
How does shutter speed affect motion and blur?
A fast shutter speed will freeze motion, while a slow shutter speed can cause motion blur. Even if you’re photographing a still subject, your hand shaking ever so slightly is enough to ruin a long exposure. To avoid blur while on high shutter speed, use a tripod.
There are two different types of blur that can be amplified by high shutter speeds.
Motion blur is self-explanatory. It’s a blur that occurs in a picture when photographing moving subjects. If your shutter is open for three seconds, the amount of movement that occurred in that amount of time will be captured in the photo. So if you photograph an airplane at a shutter speed of three seconds, you’ll see three seconds worth of movement – it’ll look something like a smear. However, if your shutter speed is set to 1/300th of a second, you’ll only see 1/300th of a second worth of movement – almost none at all. So if you’re photographing a moving subject, keep your shutter speed low.
If you’re photographing a still subject, however, that doesn’t mean you can set your shutter speed as long as you want. Blur caused by the movement of your hands can be seen at as little as 1/24th of a second on wide-angle cameras. This is called camera shake and the only way to prevent this is either to reduce your shutter speed or to use a tripod. A general rule for when camera shake will occur is at 1/[your focal length] of a second. So on a 35mm lens, you would use a tripod for any shutter speed greater than 1/35th of a second.
Did you know motion blur can be used on purpose for aesthetic effect? In astrophotography, it’s common to use shutter speeds of over an hour to capture the perceived movement of the stars as the earth rotates. It’s called star trails and an example is above.