It’s important to lay a good foundation, and you can learn the shutter of photography
It will take a while for everyone to be able to travel with confidence, so let us continue to learn some basics of photography at home to lay a good theoretical foundation for the actual shooting in the future. In the last article, we talked about what aperture is Let’s talk about another common term in photography: shutter.
What is a shutter
in English The name is Shutter, which is a device used to control the time of light irradiating the photosensitive element in camera equipment. The shutter is the mechanism used by the camera to control the effective exposure time of the photosensitive film, and it is an important part of the camera. We express the shutter speed in “seconds”. The shutter priority mode we see on the camera is simply the exposure value calculated by the camera’s metering system, and then how much is used according to the shutter value we set The aperture size to shoot.
Like aperture, there are many kinds of shutters, its structure, Form and function are an important factor to measure the quality of a camera. Generally speaking, according to the position of the shutter in the camera, it is divided into: front-lens shutter, inter-lens shutter, aperture shutter, back-lens shutter, mirror shutter, focal plane shutter; and according to the structure of the shutter, it can be divided into: mechanical shutter and Electromagnetic shutter, as we have entered the digital age, now we usually call the two together as mechanical shutter, and the shutter designed using the principle that the sensor’s photosensitive system does not work without power is called electronic shutter.
usually we are in After removing the lens of the SLR camera, what you see is the reflector
The shutter curtain is behind the reflector
The SLR camera we are using now It is usually equipped with a mechanical and electronic hybrid shutter, both a mechanical shutter and an electronic shutter. The mechanical shutter is a focal plane shutter, also called a curtain shutter. The operating direction of the curtain shutter is divided into horizontal and vertical directions. SLR cameras have two shutters: front curtain and rear curtain. When the photo is taken, the rear curtain opens and then opens the front curtain. After the exposure is over, the rear curtain closes the front curtain and then starts to close. After such a process, one shot is completed. This is why there is front curtain synchronization and Shooting method with second-curtain sync.
partly without reflection After the camera takes off the lens
You can see the closed shutter curtain
The electronic shutter is simple in structure and low in cost, so in the early years The compact digital camera and low-end products only use the electronic shutter method. It is designed by using the principle that the sensor’s photosensitive system does not work without power. Simply put, when the sensor is not powered, although the image field window is still open, it cannot produce images, so the camera uses an electronic time circuit to make The sensor works for a specified period of time to obtain the same effect as the mechanical shutter.
What is the shutter speed
Shutter speed we usually refer to the time from fully open to fully closed. The shutter speed range of different models of digital cameras is also different. Entry-level digital camera products only support a shutter speed range of 1 second to 1/2000 second, and now basically have a shutter speed range of 30 seconds to 1/4000 second, and can also provide longer exposure time, and higher-end The product will also have a faster shutter speed, such as 1/8000 second.
Canon official website EOS -1D X Mark III shutter unit schematic
It should be noted that due to the working principle of the SLR camera’s mechanical shutter, when we use the camera to shoot, there will be time lag problems, and exposure parameters Similarly, there is also a formula to calculate the equivalent exposure time, but as a novice, we only need to know this feature and practice to learn to “shoot” the amount of advance. After all, in actual shooting, there is no time for you to substitute the formula for calculation. , Can only be measured in advance by feeling.
The effect of shutter speed on taking pictures
Like aperture, shutter speed also has an effect on the amount of light entering the camera. The amount of light mentioned here can be understood as the effect of photo exposure The impact of exposure, we usually say overexposure and underexposure, is a manifestation of the exposure effect. In addition to special creative needs, we generally hope that the photos we take can be correctly exposed, and the parameters that affect the exposure are also determined by three factors.
Shutter1/ 1250 Aperture 8 Sensitivity 500
These three factors are: aperture, shutter, and sensitivity. As before, when discussing the impact of shutter on exposure, the default aperture and sensitivity are fixed. changing. The shutter speed determines the length of time the light enters the camera through the shutter and shines on the sensor, that is, under other conditions, the slower the shutter speed, the brighter the picture, the faster the shutter speed, the darker the picture, but you need to pay attention to When shooting with a digital camera, the longer the exposure time, the greater the chance of noise in the screen.
Shutter1/ 1250 aperture 6.3 sensitivity 100
Shutter 5s, aperture 10, sensitivity 100
And we often hear people say that if you want to shoot sports, you need to use a shutter of 1/1000 second or more. If you want to shoot foggy water or shoot busy traffic I feel that the shutter speed needs to be reduced. This is what we often call high-speed shutter photography and slow-door photography. We usually use a tripod to ensure stability during long exposures. But this is not to let us blindly use high-speed shutter or slow-door shooting. Take shooting sports, for example, high-speed shutter can freeze the frame instantly and freeze the moving objects in the picture, reflecting the athlete’s sense of strength, but relatively slow The shutter speed can record the trajectory of the subject, highlighting the athlete’s sense of speed.
What is a safety shutter?
I have to say one last thing, what is a safety shutter. The safety shutter is for hand-held shooting. Someone previously referred to 1/30s or 1/60s as a safety shutter in order to facilitate understanding and memory. It can only be said that although the starting point is good, we cannot remember that. Human hands actually shake slightly. Whether we breathe or seem to be still, there will actually be slight vibrations. In most cases, we will not be affected when we take photos, but long-time holding will magnify this vibration. , Which makes the shot picture blurred.
In fact, the safety shutter requires us to consider the focal length of the lens to calculate, The safety shutter speed is the reciprocal of the focal length, that is, the safety shutter speed = 1/focal length, which means that when you use a 50mm focal length lens on a full-frame camera, the safety shutter is 1/50s, and when you are in APS-C When using a 50mm focal length lens on a format camera, you also need to add the conversion factor of the focal length. Taking Canon as an example, you need a shutter speed of 1/50*1.6, or 1/80 second, to avoid blurring.
anti-shake mechanism It can compensate for the blurring caused by hand shaking to a certain extent.
This is a safe shutter speed without an anti-shake mechanism. If you have an anti-shake mechanism, you have exercised your arm or just There is no shaking at the moment the shutter is pressed, and clear photos can be taken at a shutter speed lower than the safe shutter speed. After all, this is only a “safe” shutter, which guarantees that you can take clear pictures with a high probability.
On the basis of learning this knowledge and having a certain understanding, We can simply summarize the role of the shutter speed as: the slower the shutter speed, the brighter the picture, which can record the trajectory of movement, the faster the shutter speed, the darker the picture will be, and the moment of movement can be recorded. After studying on paper, I finally feel shallow, knowing that this matter must be practiced. I hope that you can use the shutter speed flexibly to shoot in the future to achieve the purpose of improving your photography level.
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