We are all familiar with the distinctive camera shutter click sound. But do you know what is happening inside your device at this moment? In this article, photographer Chad Verzosa explains how the shutter works and why you hear a distinct click.
What is a camera shutter?
The shutter is a kind of gate that opens to let light into the sensor or film, and closes to stop the exposure.
Actually, the shutter is a complex mechanical device. There are different types that work differently depending on the specific camera. Let’s take a closer look at shutters in SLR, mirrorless, video and movie cameras.
How does the camera shutter work?
- DSLR shutter
The acronym DSLR stands for Digital Single Lens Reflex. This means that your camera has an optical device made up of a mirror and a prism, allowing you to see exactly what is going through the lens.
The optics of a DSLR is to place a mirror behind the lens that goes to a prism inside the viewfinder. You can think of the process as a tiny periscope that reflects light to reach your eye.
Now what is the mirror supposed to do with the shutter? Since the mirror is directly behind the lens, it prevents light from reaching the shutter. But the DSLR is designed in such a way that when you press the shutter button, the mirror rises so that the shutter can open and take the exposure.
When you press the shutter button, you hear the mirror make a popping sound as it rises. Since it doesn’t reflect light behind the lens or direct it into the viewfinder, you end up with a black screen.
While the mirror is raised, the shutter curtain drops and exposes the sensor behind it. As soon as the exposure ends, the second curtain comes down and closes the sensor. The length of time the first and second curtains are lowered depends on the shutter speed. The lower it is, the longer the shutter is open.
- Mirrorless shutter
Mirrorless cameras transfer image data from a sensor to a small electronic screen in the viewfinder so you can see what you’re shooting.
In many ways, the shutter mechanism of a mirrorless camera works similarly to an SLR camera. It also has a shutter curtain that rises and falls as you shoot. But the difference this time is how it moves and captures the image when the shutter button is pressed.
Since a mirrorless camera does not have a mirror, the sensor is completely open behind the lens. But when you press the shutter button, the shutter door goes up to lock the sensor and then down to take the exposure. Once the exposure is done, another door is pulled down from the top of the frame.
- Medium format shutter
Everyone has heard of framing sensors and full frame cameras. Crop sensors are commonly found in cheaper consumer cameras. Full frame sensors are used by most professional photographers.
But what about medium format cameras? Medium format gets its name from 120mm format cameras during the filming period. Since these cameras have a larger sensor and resolution, they are quite expensive.
Like full-frame cameras, medium format cameras also have DSLR and mirrorless versions. This means that their shutter mechanisms are also different. But high-end mid-format options often have a special shutter called a petal shutter.
Unlike other shutter mechanisms, the shutter blade is located inside the lens, not the camera body. It looks and works the same as a diaphragm, moving inward or outward rather than up and down.
The advantage of a petal shutter is that it is faster than any other mechanism that uses a shutter curtain. You can use it for high-sync flash, which can be 1/1000 second or more versus 1/200 or 250 second for mirrorless and DLSRs.
- Compact cameras and smartphones
Ever wondered where the click comes from on your compact camera or smartphone? The truth is that sound is produced electronically.
Compact cameras and smartphones do not have shutter curtains at all, which go up and down. Instead, they capture light from the lens directly onto the sensor. This is the main reason that they are smaller and can take more pictures than conventional cameras.
So, if your smartphone works without a shutter, why is it still necessary for conventional cameras? It all comes down to the quality of the photos. Cameras without a shutter tend to give grainy shots. On the other hand, cameras with mechanical shutters produce cleaner images. They better control the light that hits the sensor.
- Shutter when taking photos
As mentioned earlier, the amount of time that the shutter remains open is proportional to the shutter speed set on your camera.
Since the shutter is mechanical, it can only move so quickly when shooting. Try pressing and holding the shutter button for ten seconds and you can get a sense of how fast or slow your camera is taking pictures.
Your camera’s shooting speed is calculated using FPS or frames per second. Most consumer cameras can only shoot 5 to 8 frames per second, even if the shutter speed is 1/8000 of a second or more.
- Shutter when shooting video
Now that you know that most cameras can only shoot a few frames per second, you will understand why the shutter is never used when shooting video. Otherwise, there will be jerky movement because the shutter is not fast enough to capture natural movement.
When you record video using a mirrorless or DSLR, the shutter goes up and never comes down until you finish shooting. In video mode, the sensor becomes a “virtual” shutter, electronically scanning the light coming from the lens.
Capturing video data depends on the type of sensor in your camera. There are two main types of sensors in cameras. The first is CMOS, found in most entry-level and even professional-grade cameras. It captures video by scanning the scene from left to right and top to bottom.
The CMOS sensor scans the entire scene in milliseconds (which is fast!). However, this distorts fast motion because the scene is not recorded immediately. If you have a DSLR or mirrorless camera, try quickly rotating it from left to right and you will notice distortion – a rolling shutter effect.
The second type of sensor is called CCD and is most often used in professional video or film cameras. It uses a so-called global shutter to avoid any motion distortion. This means it captures the scene right away, so you won’t see any motion distortion in the frame.
Check the number of valves
Your camera shutter is a mechanical device, which means it can make a certain number of clicks before it stops working. The expected life of your camera shutter can be found in the camera datasheet or online.
The shutter of the average consumer camera is about 100,000 times. Meanwhile, professional ones are estimated at 200,000 or more positives. It may seem like this is not enough, but in general, most enthusiasts achieve only 25,000 detections per year. This means that their camera can last up to approximately 4 years.
Meanwhile, professional photographers often hit 50,000 or even 100,000 hits a year. This is another reason for the relatively frequent camera changes.
Yes, sometimes the shutter may break before or even after the expected number of shutter releases is reached. Like your vehicle’s mileage, the shutter life expectancy is a manufacturer’s estimate.
Understanding the mechanics of the shutter will allow you to see its capabilities and limitations. And let’s be honest: it’s nice to know what’s going on inside your device when you hear that distinctive click.