To take a sharp photo of a moving subject, the camera shutter needs to open and close before the image focused onto the sensor moves a significant amount. In other words, you need to use a fast shutter speed. However, how fast is enough? The answer depends on several factors that make it hard to predict how motion will be portrayed in the final photograph.
We will discuss the factors that affect the choice of the proper shutter speed required to take sharp photos of moving subjects.
First, let us discuss what is shutter, and its types. Then we will explain the shutter speed and its scale. Finally, we will list a guide on the recommended shutter speeds for various shooting scenarios, and the required camera setting.
What is a camera shutter?
A shutter is a device that allows light to pass for a determined period, exposing a photosensitive digital sensor to light in order to capture a permanent image of a scene
Common shutter types
The most common shutter types used in digital cameras are:
Focal-plane shutters – found on DSLR/mirrorless cameras
It is also called the mechanical shutter; it consists of two basic parts, the bottom curtain, and the top curtain. The below video illustrate the working sequence of the focal plane shutter.
The shutter mechanism of a mirrorless camera works similarly to DSLRs. It also has a shutter curtain that goes up and down as you take a picture. But the difference this time is the way it moves and captures the image as you press the shutter button.
Since a mirrorless camera doesn’t have a mirror, the sensor is fully exposed behind the lens. But when you press the shutter button, a shutter door goes up to block the sensor, and then goes down to make the exposure. Once the exposure is done, another door goes down from the top of the frame.
Electronic shutters – found on video cameras, DSLR/mirrorless, and mobile phone cameras
It is also called the electronic shutter, modern digital cameras and Mobil phone cameras operate an electronic shutter in a way where the cameras simply power on the digital sensor for a selected amount of time.
The pros of using the electronic shutter are: you can shoot quietly, without the noisy clang of a mechanical shutter, and you can get even higher frame rates during continuous shooting.
The apparent cons are having a lot of noise and it can produce some annoying ‘jello’ effects, especially when shooting video or very high-speed moving subjects. This is because CMOS sensors read pixel information from the top left of the sensor to the bottom right. The following GIF shows how the electronic shutter collects data.
What Is Shutter Speed?
Shutter speed is the measure of how long the camera shutter stays open to allow the entry of light. The shutter speed control two main parameters:
- It determines the amount of light reaching the camera sensor (exposure time), because it’s one of the three elements of the exposure triangle, the two others elements are ISO and aperture . Camera exposure is the overall brightness or darkness of a photograph. The more you expose the camera sensor to light, the lighter your photo will be overexposed (the photograph loses highlight details and the bright parts become blown out or washed out). On the other hand the less light, the darker your photo will be underexposed (the photograph loses shadow details and the dark parts are almost all black)
- Shutter speed affects also the look of your subject in the photo, if you use Fast shutter speeds; it will freeze its motion (stop the movement) and avoid the motion blur in your images.
Shutter Speed scale
Shutter speed controls the exposure time, for example, a shutter speed of one second exposes the image sensor to light for one second. This is known as a one-second exposure time.
The Shutter Speed scale is established with the exposure stops concept in mind . An exposure stop provides a universal scale to measure the increase and decrease in light exposed to the image sensor due to changes in shutter speed & f-stop.
Stopping one stop up will double the light amount while stopping one stop down will half the light amount.
The stops scale provides an easy way for the photographer to increase or decrease image brightness or adjust specific f-stop, ISO, and shutter speed settings while balancing the exposure triangle.