What is Shutter Speed? How Does it Work?


I talk to a lot of newer, less experienced photographers and whenever we get to the topic of the different priority modes on a camera, shutter speed comes up as one of the most popular. While many budding photographers have heard of shutter priority mode, many don't quite grasp what it does or what it's capable of. With this in mind, I thought I'd write this post to help explain a few things.

Shutter priority mode is the mode that controls the camera's shutter speed. On my Canon Rebel T7i, the indicator on the dial is Tv. The shutter itself is one of the mechanisms in a camera and lens setup that controls how much light enters onto the camera's sensor. It also controls how much potential blur or sharpness a photograph will include. I'll get to that in a bit.

As I just mentioned, to access shutter priority mode on my Canon Rebel, I would turn the dial on top of the camera to the Tv (Time Valuation) setting. On many Sony DSLR cameras, the setting says S. This is also true for Lumix and Nikon. As for Fuji cameras, things are a bit more complicated. You'd have to turn your lens to a particular setting and then turn the dial on the top of the camera to a designated shutter speed, which, in effect, activates shutter priority. Please check your camera's manual for specific model instructions.

Okay, so what exactly does the shutter inside of a camera control again? Well, the shutter is the thing that blocks light from getting to your camera's sensor. When light makes it's way to the sensor, it's recorded as an image and there you go. You've got a photograph. If the shutter moves out of the way for a very, very brief moment of time, only a tiny bit of light will make it to the sensor. This can create dark images, but also, since the shutter movement was so fast, there won't be much blur at all in the photo, even if the camera or the subject was moving. It's sort of light blinking your eye very quickly or moving under a strobe light. Things will be clear, but they may be dark.

If the shutter moves out of the way for a longer period of time, much more light will make its way to the sensor, but more blur might be introduced into the photo. This is why people suggest using a tripod to keep your camera still if you've working with a slow shutter speed. Although, there may be times when you actually want blur, as in when you're panning a subject like a motorcycle racing around a racetrack or if you're going for light trails or something.

Let me give you some examples of what you might want to use a faster shutter speed for. Since fast shutter speeds essentially freeze time, you can capture an action as it's happening. Have you ever seen those photos of hummingbirds that have their wings perfectly still? In mid air? Those shots were taken using a shutter speed of probably around 1/1000th of a second. This type of shot can go up to 1/8000th of a second, depending on what you're taking a photo of. Hummingbirds are great. So are flying insects. Very interesting photographic styles. Fast shutter speeds basically freeze time so you can see exactly what was happening that split second.

Conversely, slower shutter speeds allow us to see what was going on over a longer duration of time. Think about all of those silky waterfall photos you've seen. Those may have been taken with a two second shutter speed or even slower. If you'd like to take that picture of the motorcycle racing around the track and you'd like to show off how fast it was going, you may want to set your camera to a 1/4 second shutter speed and track the motorcycle and then snap the photo. Doing this will show the bike as clear, but the background as blurry. That shows a lot of movement. Also, if you set the shutter speed for an even longer duration, such as 30 seconds, you'll be able to capture tail light trails on passing cars. Or if you want to go even longer than that, you can capture star trails in the night time sky. As you can see, shutter priority mode can truly open up a world of creativity.

When it comes to dealing with too much or too little light, shutter priority mode can help as well. I've photographed on very bright, sunny days and I've had to set a faster shutter speed, just to cut down on all that light that was coming through my lens. If I didn't, my photos may have come out over exposed. As for darker environments, slower shutter speeds may help to let in some of that necessary light. So there's a lot to think about when it comes to photography in the way of movement and creativity as well as how and how much light is going to make it to your sensor for a proper exposure.

I hope I explained some of what shutter priority mode is when it comes to photography. I know this is sort of a big topic, so I'm happy to answer any questions you might have on it. Just ask my down below. Thanks!