Who can talk about the relationship between shutter and aperture?

From the perspective of daily life photography, the main function of aperture is to control the depth of field and exposure. The larger the aperture, the shorter the depth of field, and the smaller the aperture, the longer the depth of field. Another main function of the aperture is to control exposure. The larger the aperture, the greater the exposure, and the smaller the aperture, the smaller the exposure.

The main function of shutter is to control exposure and "freeze" moving images. The slower the shutter speed, the greater the exposure, and the faster the shutter speed, the smaller the exposure; The faster the shutter is, the more you can grasp the instantaneous static state of the moving object.

If you want the scene to achieve the expected image, you must rely on the close cooperation of aperture and shutter speed. Several technical indexes of photography-correct exposure, clear image, rich layers and prominent theme-can only be achieved by close cooperation between aperture and shutter.

Problems needing attention when choosing aperture

Choosing the aperture according to the depth of field should be the basic principle when taking pictures. Some people mistakenly think that the longer the depth of field, the better the clear range. Actually, this is a misunderstanding. The correct statement should be that the clear place should be guaranteed, and the unclear place should not be clear.

Problems needing attention when using shutters

If you use an automatic exposure camera with aperture priority, you can control the shutter speed through the aperture: a large aperture means fast speed; Small aperture means slow speed. General camera, shooting general scenery, should determine the aperture, according to the weather, light conditions to determine the shutter. If you shoot a moving object, you must first choose the shutter, and then determine the aperture according to the shutter. Sometimes a high-speed shutter is used to take a dynamic picture into a "frozen" state. Sometimes, if you want to photograph the motion of a moving object, you must use a slower shutter speed.

There are many opportunities to use zoom lenses now. It's big, heavy and long, and it vibrates easily when you press the shutter, so you should hold the lens tightly instead of just holding the fuselage like a standard lens. When the shutter speed is less than the reciprocal of the focal length, a tripod should be used.

Shutter priority! It has nothing to do with jitter! The quality of the photo is related to the exposure, that is, how much light is needed to make the ccd get a clear image. Exposure is related to light passing time (determined by shutter speed) and light passing area (determined by aperture size). Then, in order to get the right exposure, we need the right combination of shutter and aperture. When the shutter is fast, the aperture will be larger; The aperture is smaller when the shutter is slow.

Shutter priority refers to the exposure value calculated by the automatic metering system of the machine, and then automatically determines how much aperture to use according to the shutter speed you choose.

Aperture priority refers to the exposure value calculated by the automatic metering system of the machine, and then automatically decides how many shutters to use according to the aperture size you choose.

The larger the aperture, the more light passes through per unit time, and vice versa. Aperture is generally expressed as the letter "F+ value", such as F5.6, F4, etc. It should be noted that the smaller the value, the larger the aperture. For example, F4 is larger than the aperture of F5.6, and the difference between two adjacent apertures is twice, which means F4 is twice as big as that passing through F5.6. Relatively speaking, the definition of shutter is very simple, that is, the time allowed for light to pass through the aperture is expressed by numerical values, such as 1/30 seconds, 1/60 seconds, etc. Similarly, the difference between two adjacent shutters is twice.

The combination of aperture and shutter forms exposure, which is not unique under certain exposure conditions. For example, the current normal exposure combination is F5.6 and 1/30 seconds. If the aperture is increased by one step, that is F4, the shutter value at this time will become 1/60, and this combination can also achieve normal exposure. Although different combinations can achieve the same exposure, the pictures taken have different effects. The concept of "depth of field" is involved here. The so-called depth of field means that when the lens focuses on the subject, the subject and its scenery before and after have a clear range, which is called depth of field.

Aperture priority is to manually define the size of the aperture, and then use the camera's metering to obtain the corresponding shutter value. Because the aperture directly affects the depth of field, this mode is most widely used in ordinary shooting. When shooting portraits, we usually use large aperture and long focal length to blur the background and get a shallow depth of field, which can highlight the subject. At the same time, a larger aperture can also obtain a faster shutter value, thus improving the stability of hand-held shooting. When taking photos such as scenery, we often use a smaller aperture value, so that the range of depth of field is wider, which can make the distant and nearby scenery clear, which is also applicable when shooting night scenes.

Contrary to aperture priority, shutter priority is to obtain aperture value through camera metering when the shutter is defined manually. Shutter priority is mostly used to shoot moving objects, especially sports shooting. Many friends find that when shooting moving objects, the subject is often blurred, mostly because the shutter speed is not fast enough. In this case, you can use the shutter priority mode, roughly determine a shutter value, and then shoot. And the motion of the object is generally regular, then the shutter value can also be roughly estimated. For example, the shutter speed for photographing pedestrians is only1125 seconds, while it takes11000 seconds for photographing falling water droplets.

In the case of aperture priority, we can easily control the depth of field by changing the aperture size, while in the case of shutter priority, using different apertures can achieve good shooting results for moving objects. Both should be used flexibly to meet our shooting needs in different situations. Like traditional cameras, the aperture range and shutter speed of digital cameras are very important when shooting, but for ordinary commercial and domestic digital cameras at present, people only care about how to choose the shooting scene because of the full automation of the cameras, but don't pay much attention to the aperture and shutter speed automatically controlled by the cameras. However, if you buy a digital camera, you'd better compare the aperture range and shutter speed of various digital cameras, because the aperture and shutter will cooperate to control the overall light entry range of your digital camera, which means that it will affect whether your camera can get good results in various light conditions. At the same time, the shutter speed will directly affect the effect when you shoot dynamic images, and the aperture range will affect the depth of field of your shot images.

The process of taking pictures is that after the camera opens the shutter, the front image is projected onto the CCD photoreceptor of the digital camera through the lens, and the photoreceptor records the image information on the memory card of the camera through the digital-to-analog converter. This process is the same as the traditional camera exposure process. However, if you want to get rich images, you must control the amount of light projected on the CCD sensor so that the details in the photos can be described correctly. From the darkest to the brightest area, there are rich levels of expression, and there is a gradual transition between light and dark, which is not completely black and white. In addition, the contrast and freshness of the works also have the best performance. Too much light leads to exposure transition and the image is obviously bright; On the other hand, if the CCD absorbs too little light, it will be underexposed, the whole photo will be dark, the details will be lost, and the photo effect will be quite bad, so it is very important to get the appropriate exposure when shooting.

Like traditional cameras, digital cameras are used to control exposure, that is, "aperture" and "shutter". Aperture is the aperture through which light passes through the lens. The larger the aperture, the more light can be projected per unit time, and the shutter is the time for light to pass through the lens. The shorter the time, the smaller the exposure.

Like traditional cameras, digital cameras have an aperture placed in several lenses of the lens, which is composed of several metal sheets, and the aperture is adjusted by the movement of the metal sheets. Anyone who has used a traditional reflective camera knows that we can find the aperture value f on the lens. Usually, the aperture scale is:1.4,2,2.8,4,5.6,8, 1 1,16,22 ... The larger the aperture series f is. But at present, in some digital cameras, the aperture is not set according to the above series, but according to f2.8, f.5.6, f 1 1. At this time, the light input of the upper and lower layers is not only twice as bad.

As mentioned earlier, the aperture is the size of the aperture when light passes through the lens. However, this is only a general statement. The aperture size should also consider the focal length of the lens itself. The lens length of a long focal length lens (telescope head) is longer, and the distance of light entering the CCD is longer, so the light projected on the CCD is weaker, so the aperture of a long focal length lens is often slightly smaller. If you want to make a large aperture lens, you must increase the aperture and increase the unit light intake. However, due to the difficulty and high manufacturing technology of large aperture lens series, this kind of lens is usually expensive. Because the aperture series f is calculated by the ratio of aperture size to focal length, as long as the aperture series is the same, the amount of light entering is the same whether it is 35 mm or 200 mm

Shutter speed values are usually marked as: 1, 2, 4, 8, 15, 30, 60, 125, 250, 500 ... These are the reciprocal of 1 second, so 15 means 650. Just like an aperture, the shutter speed of each frame is twice different. For example, the light value of the shutter 1/500 seconds is half that of 1/250 seconds, and only 1/4 of125 seconds.

Because both aperture and shutter can be used to control the exposure, as long as the aperture value f is determined, the exposure can be corrected by the shutter speed. On the contrary, you can also determine the shutter speed to be used first, and then get exposure by adjusting the aperture. Fortunately, in the adjustment of the amount of light, the concept of twice is used to control, which makes it easier for us to adjust the appropriate exposure. For example, if the correct exposure is F/65438+, when the shutter is 1/30 seconds, if you want to raise the shutter to 1/60 seconds, then the aperture will be opened to f/8, because when the shutter is from 1/30 seconds to1/.

However, because the aperture and shutter have their own advantages, the effect produced by each collocation is different. We must choose the most suitable combination according to the needs of the subject and the way we want to express ourselves, so as to give full play to the practical significance of aperture and shutter.

According to shutter speed, it can be divided into high-speed shutter and slow shutter. Usually, a high-speed shutter can "fix" a moving object, and the action details and textures of the fixed object are vividly portrayed, making the object more stereoscopic. Usually, the shutter speed is from 1/30 seconds to 1 second, and even the B shutter above 1 second belongs to the range of slow shutter. The common methods of slow shutter are: the first method is to fix the camera, and then use the slow shutter speed to make the moving object produce blurred images, so that the clarity of the background (still life) can better set off the dynamics of the theme. The second method is to make the camera translate or shift with the direction of the object movement. In this way, contrary to the first method, the background will become quite vague, while the theme will be a little vague but clear, which will also separate the subject from the background. The third kind, that is, the whole photo is blurred without stopping, and the phase machine is shaken quickly. These three methods have their own characteristics, and how to use them in time depends on everyone's preference.

We often shoot the city at night with a slow shutter, because the driving vehicles leave traces of red and white lights, and dozens of lights gather into a long queue, which is very beautiful and depicts the prosperity of the city that never sleeps. It is still used to shoot running water, and it feels quite soft and delicate.

When choosing a slow shutter, you should pay special attention, because the exposure time at each stage is very different, unlike the high-speed shutters of 1/250 seconds and 1/500 seconds, the shooting effect is difficult to compare. When shooting a flowing scene with a slow shutter, if the shutter is too fast, the scene will freeze unexpectedly; If the shutter is too slow, it will appear too hazy and lose the desired effect. So, if you try to shoot every slow shutter, you can get the ideal work and see the difference.

Compared with the shutter, the aperture is a little more complicated. In addition to adjusting exposure, aperture is also the most important thing to control the size of the "depth of field" of the picture. The so-called "depth of field" means that focusing makes the image clear, and the areas within a certain distance before and after the focus can be clearly displayed. We call it depth of field. The longer the depth of field, the larger the range that can be clearly presented. On the contrary, the smaller the depth of field, the more blurred the foreground or background, which is a hazy phenomenon caused by poor focus. From the optical theory, under the focal length of the lens, only the plane at the object distance can be clearly shown, and the scenery outside this plane will be blurred.

There are three factors in the depth of field of an image: (1) The depth of field is inversely proportional to the length of the focal length, in other words, the longer the focal length of the lens, the shorter the depth of field. (2) The depth of field is proportional to the shooting distance of the scene. The closer the camera is to the scene, the shorter the depth of field. (3) The depth of field is proportional to the aperture series. If it is inconvenient to keep the focal length of the lens and the shooting distance of the object, the larger the aperture, the shorter the depth of field. That is to say, when the aperture changes from f/111→ f/8 → f/5.6 → f/4, the depth of field becomes shorter and shorter, and the scenes outside the depth of field become more blurred. This hazy beauty is different from the blur caused by camera vibration. Full of elegant and soft luster, like rendered colored ink, it lightens the tone, can create a considerable atmosphere, has a sense of perspective out of the theme in depth of field, and has the characteristics of setting off the main body. Therefore, it is often used in portrait photography, and the background of the model is blurred, which makes people focus on the beautiful model. At the same time, because of the use of large aperture, there can be more light. In order to improve the shutter speed, prevent the camera from shaking, and make the image sharper and clearer, if you want to capture the environment and atmosphere at that time without the help of a tripod under the dim light source, or you can't use a slow shutter, you use a place with a large aperture, which destroys the atmosphere of the picture. Therefore, the large aperture lens has always been one of the equipment used by film friends.

If the aperture is smaller, from f/5.6 → f/8 → f/1→ f/16 → f/22 ..., the range of depth of field will be larger, the description of the scene will be more realistic and full of authenticity, and the picture quality will be clearer and Ming Rui than that of a large aperture, and because of the range of depth of field, In addition, the small aperture can reduce the aberration of poor image connection or uneven light transmission of the lens and obtain high-quality works. There is also a small aperture, which can reduce the shutter speed and create a sense of flow through a slow shutter.

For professional digital cameras, you can generally control the aperture and shutter speed of the camera manually, but for commercial and household digital cameras, because the camera automatically controls the aperture and shutter speed, you do not need to control it yourself, which is very good for non-professional users. However, it can be seen from the above analysis that when users choose a digital camera, the larger the aperture range and shutter speed range of the digital camera, the better. In addition, the aperture should be set continuously according to the normal series, rather than jumping. In addition, it should be noted that the shutter speed of digital cameras is generally different when the flash is turned on and off.