What is the difference between electronic and mechanical shutter. Noiseless mode can spoil you photos - Stanislav Vasiliev

Both a conventional film camera and a modern digital camera have an optical lens system, a diaphragm and a shutter. We can say that from the point of view of the basic scheme of the photographic device operation, little has changed with the advent of digital phototechnics: light rays are collected in the lens and then directed through the aperture (diaphragm) to the photosensitive element (sensor). In this scheme, the shutter and diaphragm are elements that are invisible to the photographer's eyes, which, nevertheless, have a huge impact on the result of the survey. Why in modern digital photographic technique these elements, well-known even on film devices, have been preserved? What are they needed for? How does the aperture and shutter work in a digital camera?

Purpose of the shutter and diaphragm

Gate This is one of the main mechanisms of a digital camera, which is responsible for letting light rays pass to the photosensitive element (matrix) for a predetermined period of time when the photographer presses the shutter button. The main purpose of the shutter is to regulate the duration of the passage of light through the camera's optical system.

The time at which the camera shutter opens is called exposure time or exposure time. If the shutter speed is less than a second, it is indicated as the denominator of the fraction, denoting a fraction of a second. For example, 1/125 seconds or 1/30 second. The closures installed in digital cameras are able to close and open at a high speed, thereby adjusting the time of exposure of the matrix, i.e. exposure, with high accuracy.

The longer the shutter speed, the more light it will get on the photosensitive element of the camera. From the photographer's point of view, the camera shutter should have high accuracy of operation, reliability in operation under various shooting conditions and a wide range of exposures. In modern digital cameras, the shutter is used not only to control the shutter speed, but also to protect the matrix from exposure during image reading or before the exposure begins.

Diaphragm It is a round variable hole that is inside the camera lens. The photographer can vary the diameter of the hole, thereby regulating the flow of light entering the matrix of the digital apparatus. The value of this hole is determined by the diaphragm number: the larger the aperture opening (small diaphragm number), the more light falls on the matrix and vice versa.

In digital cameras, the diaphragm number can be varied within a fairly wide range, for example for the Tamron AF 18-270mm f / 3.5-6.3 Di II VC lens, from f / 3.5 to f / 6.3. In addition, the diaphragm exerts its influence on the depth of field of the image, allowing the photographer to control the creative process. As already understood, shutter speed with aperture is interdependent parameters. Together they constitute the so-called exponential: if one of these parameters decreases, another one increases.

Photographic shutter: operating principle and views

At the moment when photography is taking place, the shutter of the camera opens. Light rays pass through the lens, get on the diaphragm, due to which the amount of light is regulated, and, eventually, reach the photosensitive element. After the light enters the matrix of the digital camera, the exposure of the frame begins. Then the shutter closes. After a moment, the camera will be ready to shoot the next frame. Opening and closing, the shutter as well as the diaphragm, provides a change in the amount of light falling on the matrix.

Naturally, no matter how perfect the photographic shutter, it requires a short, but still some time, to open up. It also takes some time to close it. In this regard, we can distinguish three stages or phases in the work of the photographic shutter.

The first phase is associated with the opening of the active lens opening. Next - this is the phase of the full opening of the active hole. And, finally, the last phase is the closing phase, that is, a certain period of time from the beginning of the reduction of the active hole to its full closure. From here it can be understood that during this whole shutter cycle the active hole of the lens remains completely open only some time.

In this regard, one of the most important characteristics of the shutter is optical efficiency (EFFICIENCY), which determines the ratio of the amount of light that has passed during the shutter's operation to the amount of light that could pass through the "ideal" shutter over the same time interval. The more the value of the coefficient of efficiency approaches unity (that is, to 100%), the better the shutter operates. In other words, the shorter the time during a given shutter speed will go to open and close the shutter, the longer the lens opening will be fully open, which means that more light will pass through the lens. In this regard, we can say that a good photographic shutter is able to fully reveal the lens blur.

All the shutters of digital cameras have special controls, through which you can set the shutter speed required for a given photography. However, a suitable shutter speed can be determined by the camera and automatically. In many devices there is a special mode of fully manual control of the opening time of the shutter (Bulb), by means of which the bolt can not only open, but also be closed strictly by the command of the photographer. This mode is very important when shooting at long exposures, when the camera is mounted on a tripod.

By its design and principle of operation, the shutters in digital cameras are divided into the following types:

- Electronic shutter

If a mechanical shutter was installed in film cameras, which opened and closed the curtains, limiting the effect of light on the film, then in digital cameras its role is performed by an electronic shutter. Almost all digital cameras are equipped with exactly the same electronic equivalent of the shutter, which is built right into the camera sensor.

It is a kind of switch that includes a sensor to receive a light stream at the right time and turn it off by the processor's command. The electronics and the camera processor fully control the operation of such a shutter. The peculiarity of the electronic shutter is that the light on the matrix gets constantly, which allows, in particular, to transfer the image from the matrix to the LCD screen of the camera. When the electronic shutter is activated, the image from the camera matrix is read out for a certain period of time. This interval between the zeroing of the matrix and the instant of reading of the electronic information from it, and in this case, constitutes the holding time.

The advantage of using electronic closures in modern digital photographic equipment is that they can achieve very short exposures. Such a shutter, in particular, is able to work out the shutter speed up to 1/8000 or 1/15000 s. In addition, the electronic shutter operates noiselessly and without vibrations.

However, he also has his shortcomings. This, first of all, low quality, associated with various image distortions, the cause of which is the sequential reading of the cells of the matrix. Due to constant illumination, the electronic shutter is characterized by a tendency to halos, blooming and other unpleasant effects. That is why in the advanced compact cameras and professional digital devices, in addition to the electronic shutter, traditional mechanical is also necessarily present. In the cheap models of digital cameras only electronic shutter is used.

Despite the appearance of digital photographic equipment with electronic closures, controlled by other processors, the mechanical shutter is not a thing of the past. It is still used in decent digital cameras, only now it works in tandem with electronic. Synchronous operation of these two gates makes it possible to provide short exposures and at the same time avoid the appearance of a halo around the contrast images. In professional SLRs and advanced compacts, the electronic shutter is used only for ultrashort exposures, but mainly mechanical.

In addition to the fact that the mechanical shutter doses the light that enters the photosensitive element of the camera, it also serves to further protect the matrix from the ingress of dust and dirt onto it. After all, the matrix is the most expensive element of a digital camera, especially when it comes to a professional camera. The mechanical shutter itself has a certain service life and eventually it breaks down.

By its design, mechanical closures are traditionally divided into two types - central and curtain (shutter-slotted) gates. The center shutter, as a rule, is installed between the lens of the lens. It uses shutters in the form of thin petals, which open the light hole of the lens from the optical axis to the edges, and close in the opposite direction. This ensures a uniform distribution of illumination throughout the field of the frame. The greatest efficiency is possessed by that central shutter, in which the sunblinds act with the greatest speed.

The central shutter has many advantages: no distortion of the image as a result of the work, a uniform distribution of illumination and good resistance to temperature fluctuations. However, compared with curtains, the central ones have a lower efficiency and a lower minimum speed, i.e., less instantaneous exposure.

As for the curtain or curtain-slotted shutter, it uses a light-tight curtain consisting of two parts separated by a transverse slit. In this slot, and penetrates the light coming from the lens. When the shutter releases, the shutters move one after another: the first light flap opens the frame, and the other, respectively, closes it. The exposure here depends on the width of the slit.

The main advantages of the curtain are high efficiency (can reach 95%) and the ability to work out short exposures (up to 1/1250 s in some models). But when shooting fast moving objects, the use of a curtain-slit shutter often leads to the displacement and distortion of individual image elements. Curtains are also characterized by the fact that they are more prone to temperature fluctuations.

- Electron-optical shutter

Along with the electronic shutter, some models of digital cameras use a mechanical shutter instead of a mechanical one. It is a liquid crystal, which is located between two parallel polarized plates. Through it, the light flux passes to the camera's electron-optical converter. When tension is applied to thin electroconductive deposition of the inner surface of plates, electric field, which changes the plane of polarization of the liquid crystal by 90 degrees. As a result, the maximum opacity of the crystal is ensured and, as a consequence, the liquid crystal shutter is closed. In the absence of the same voltage, light passes through the liquid crystal to the matrix. Since there are no mechanical elements, the electron-optical shutter is characterized by a rather high reliability and simplicity.

Aperture of the digital camera

The diaphragm in its classical form is arranged as a light-tight shutter formed by thin metal lobes shifting towards the center of the lens. This is the so-called iris diaphragm. Thin petals, arranged in a circle along the rim of the lens, rotate and thereby increase or decrease the hole through which light enters. The more open the petals of the diaphragm, the more light passes to the photosensitive element. Control of aperture in digital cameras can be carried out in manual or automatic modes.

Manual control of the diaphragm is usually realized in the form of a ring on the outer surface of the lens rim, on which the scale of the diaphragm numbers is marked. When the diaphragm ring rotates, the petals shift. In this case, each transition from one value of the diaphragm number to an adjacent value ensures a change in the amount of light passing through the lens exactly twice. Very convenient is the aperture priority mode, when you can independently set the aperture, and all other settings the camera will automatically set. The control of the diaphragm in the automatic mode is carried out through the camera electronics, proceeding from the analysis of the specific conditions of photography.

The change in the diaphragm influences immediately two key properties of the image - aperture and depth of field. By aperture is understood the maximum amount of light that a given lens can transmit. In daylight conditions, adjusting and controlling the diaphragm of a digital camera is not difficult. But in conditions of insufficient illumination, for example, when shooting in a dark room, the photographer has to shoot with a large aperture aperture, so that the photo does not turn out to be dark. This requires a flexible diaphragm control to compensate for the lack of light.

The size of the diaphragm is determined by the area, which in the photo will look sharp. In other words, it depends on the diaphragm what the background will be in the picture - blurred or sharp. For example, a small aperture is used to blur the background and perspective. Depth of field extends from the center to the edge of the image, respectively, the closer to the edge of the picture, the more blurred the object will be. On the contrary, a large diaphragm is used in those cases when everything should look sharp in the photograph. In general, the control of the diaphragm gives the photographer complete freedom of action and a wide field for creative experiments.

Speaking of the shutter and diaphragm of a digital camera, it should be noted that in some modern cameras the diaphragm can be combined with a central lobed shutter. In this case, the aperture mechanism is triggered exactly at the moment of the shutter release, and the shutter lobes at the same time diverges by a distance that corresponds to the set aperture value. But such combined diaphragm shutters with the adjustment of the size and duration of opening the light hole are installed, mainly, in the entry level chambers. Although they provide greater compactness of photographic equipment.

The problem is that due to its design, the integrated shutter-diaphragm mechanism is able to work out only exposure pairs such as long exposure - the minimum relative aperture or the short exposure - the maximum relative aperture. Such a linearity of the parameters turns out that, for example, in conditions of insufficient illumination the camera will use long exposures with an open diaphragm, which, naturally, will negatively affect the quality of the photo image. In addition, diaphragm shutters are not able to provide a wide range of shutter speeds and aperture values.

The shutter and diaphragm remain the basic mechanisms of the photographic apparatus in the age of digital technology. Along with the characteristics of the lens, the shutter and diaphragm in many ways predetermine the quality of the photo image. The ability to manually adjust the aperture and shutter speed provides the photographer with space for creative experiments and fine-tuning their digital camera for specific shooting conditions.

Neither resembling anything, and thus familiar to modern man - the sound of the shutter (Shutter) of the camera. This sound became so recognizable that it became synonymous with photography, it was imitated on digital analogs and mobile phones electronically. Have you ever thought about the mysterious process behind this sound?

Shutter operation in a SLR camera

There are three main components of the shutter in the camera: a mirror, a lower curtain and an upper curtain. When you look through the viewfinder, the so-called SLR cameras, you essentially see the image directly from the lens passing through a group of mirrors. When you press the shutter release, the mirror is raised for a short time so that the light enters the matrix / film. That's why the picture disappears in the viewfinder - at this moment it becomes dark.

After the mirror rises, a small curtain starts moving from top to bottom, exposing the matrix / film behind it. After that, another shutter falls down, covering the matrix / film entirely. Depending on the set shutter speed, this process can vary with time. Sometimes it can be very fast.

So - the second curtain closes the matrix, the mirror falls down, returning to its original place, the curtains occupy the starting position. All this action, from the moment the mirror is raised to its return, is the shutter release cycle.

sLR cameras

Shutter without a SLR camera

In contrast to SLR cameras, in non-mirrored - there is no mirror system, or penta prism. Actually, that's why this type of camera is called without a mirror. The matrix in such devices is constantly exposed to light passing through the lens. For this reason, without a SLR camera, either a LCD screen or an electronic viewfinder is used.

As soon as the user presses the shutter button, the lower curtain rises up to close the matrix. Then, the same curtain begins to fall, and at this moment, the exposure takes place. Further, the second curtain is lowered and the matrix is closed. After the second curtain closes the matrix, the exposure is completed and the curtains return to their original position.

A graphical example of one cycle forwithout mirror chambers

Do you need a mechanical shutter?

Before the era of digital matrices, it was very important to equip the camera with a shutter. This was connected with the fact that the film can not simply be turned on and then turned off. Photographic film and film are very sensitive to light and any, even a short light effect on it is fraught with consequences. Of course, at the present time, technologies allow you to do without mechanical shutter in cameras of a certain category.

A classic example of such, without shutters, are user class cameras - handheld devices and mobile phones. Cameras of this kind are usually noisier than their classical counterparts. This is connected with the fact that in such cameras the power to the matrix is constantly supplied. It must also be taken into account that the higher the ISO value, the more noisy the image will be, and this applies to any types of cameras.

Most likely in the near future, the technology will allow to obtain professional-quality images using cameras without closures, but at the moment, they are still far from professional quality.

The mechanism of the shutter when shooting a video

The mechanism of the shutter for video shooting, is very different from the principles of the shutter in photography. This is due to the fact that a conventional camera is capable of activating the shutter mechanism, about six times per second. The trigger mechanism is simply too slow for a video, which usually records 25 or 30 frames per second. Therefore, the curtains and mechanisms of mirrors, all the time are in the open state.The gate is realized, based on the adjustment of the time of reading the information from the matrix. This is the electronic shutter. The exposure is determined by the time between the dropping of the matrix and the moment of reading the information from it. Accordingly, the matrix is reset after each frame.

What is Global Shutter?

Perhaps the title suggests that this is one of the types of shutter, but in fact the interaction of Global Shutter and the matrix is very important. When it comes to the matrix of a video camera, there are two main types of matrices that you need to know about - CMOS and CCD.

CMOS - CMOS (complementary structure of metal-oxide-semiconductor) matrix, is most common in the category of semi-professional cameras. And we must admit, they are very problematic. This is due to the principle of the CMOS matrix. It reads information from the pixels moving from the upper left corner to the bottom right. This creates a problem, because if the subject moves fast at the time of shooting, then the output is a distorted image. In such conditions, Rolling Shutter (as it is designated), creates the effect of "jelly", which is a marriage, if speak from a professional point of view. And this effect is especially evident when shooting a video.

Another type of matrix - CCD -CCD (charge-coupled device), records the entire frame. This is the so-calledGlobal Shutter. How Global Shutter works similar to the operation of the film camera - the frame is recorded entirely, thereby eliminating the distortion of the image. In this wayGlobal Shutter gives a more realistic and high-quality image.

Now on the mirrorless began to put an electronic shutter. This thing can spoil you all the shooting, if you do not understand where it is appropriate, and where not.

This anigiphka shows the classic jamb of the electronic shutter. It was shot in 1 / 18,000 seconds from hands, at f / 1.2 with a focal length of 84mm (EGF) and a minimum ISO. As you know, there was too much light to shoot on such an open diaphragm, and on a classic camera, limited to a shutter speed of 1/8000 seconds (and many DSLRs and HPCs at best 1/4000) would have to use a neutral filter, for which ....

At the PPC, which I did this survey, it was possible to turn on the electronic shutter, with which an exposure of up to 1 / 32,000 seconds became available. It seems to be good, but ... as you can see, there are nuances.

The bottom line is that the time when the pixels are no longer read at the beginning of the matrix, and when at the end, it is essentially different. It turns out that part of the picture was taken earlier, and some later, and any movement in the frame is deformed. That's why for cameras with the possibility of using an electronic shutter will be VERY superfluous stabilizer - in the lens or on the matrix. Stub allows you to keep the picture smoothly and "break" more or less static plot is more difficult.

When shooting with wiring, when using an electronic shutter, there is such an amusing effect:

All except the main "slave in the frame" of the object of shooting is tilted. And judging by the slope, by the way, the reading cutoff happens from the top to the bottom. That is, first it is removed top part frame and gradually fixes to the bottom. There is also a third problem.

Another electronic shutter is afraid of daylight lamps, because of their flickering - it can get the effect when the brightness in the photo floats on the frame with stripes, as if the picture was taken through the blinds. Here too much depends on the light and the sensor, the effect can be strongly pronounced or barely noticeable only when turning over.

Finally, in most modern PCs, in the electronic shutter mode, you can not shoot in the studio. The effect is the same as when selecting the wrong speed of X-synchronization - part of the frame is lit, and part in total darkness.

In general, I will sum up. The electronic shutter piece is cool - it allows you to use the camera in a "noiseless mode", shoot unnoticed, use shorter exposures, but at the same time it can spoil blood. With him, you should not shoot dynamics, and even people jumping on a trampoline. You can shoot ballet in this mode, static portraits in the bright sun, too, but as soon as the movement comes ... the problems begin. And these problems strongly depend on what kind of camera it is and what kind of sensor it is.

As I understand, the sensors are being improved, and for example, the Sony RX100 M4 has been equipped with the newest composite sensor, in which the whole picture is read right away. I have not seen the camera yet, according to the opinions of my Western colleagues, it has practically no sound problems with the electronic shutter, and for the same reason there is no rolling-shutter when shooting video. But this is a soap dish, though. Let's see when multilayer sensors get to cameras seriously.

In terms of current mirrorless, everything varies greatly, it is necessary to check the models individually. Some problems are more pronounced, others less - it depends, obviously, on the speed with which the data from the matrix is read.

Both frames - rejection from backstage from the filming of the clip on the single "Summer" Rodion Gazmanov , which the . And we'll post the backs a bit later, there are very cool moments where I managed to check many of the chips from one of the brand-new mirrorless ones I currently have on tests. In the plans, quick reviews on the Fujifilm X-T10 and Sony A7-II, well, on the approach 42-megapixel A7R-II.

Soon lay out a review of the Olympus 75mm f / 1.8, on Monday I plan to review the new 14-150. Everything is already written, it remains to turn up here.

Well, on the topic of the post I wanted to ask: are you using the silent mode of the camera or would you like to use it?

Dear friends, today we want to tell you what is the difference between electronic and mechanical shutter. In some cameras, you can choose between the descent of the electronic and mechanical shutter. The electronic shutter allows you to control the exposure, including turning the camera's matrix off and on when it is triggered. The mechanical shutter uses the traditional front and rear curtains, located in front of the matrix, which open and close to adjust the exposure.

Electronic shutter
Silent work
Its dignity is silent operation, since internal parts do not move during exposure setup. This is important in cases where the sound of a mechanical shutter release can attract the attention of a photographed object, for example, when shooting from a close distance of wildlife, sports events or when the photographer needs to remain unnoticed.

Increased frame rate
The electronic shutter does not have mechanical parts, so you can increase the frame rate compared to the frequency obtained with the mechanical shutter. For example, the camera Nikon 1 V3 can shoot at a speed of 20 frames per second with an electronic shutter and 6 frames per second - using a mechanical.

Reduction of jitter / lubrication
The movement of the front curtain of mechanical closures or the impact of the mirror cause slight vibrations, which in camera with high resolution can cause camera shake or image blurring. When shooting with a tripod using an electronic shutter, camera shake and image blurring are reduced because physical objects inside the camera do not move.

Mechanical shutter
Reducing the distortion of the shutter
When shooting with a short shutter speed by fast-moving objects or fast panning, the CMOS matrix can create a distortion of the shutter. If an electronic shutter is used, the CMOS sensor is turned on and sequentially scans the line behind the line, and when shooting fast moving objects, the distortion is displayed in the picture, for example, the trail of the player's golf driving the stick down is visible. If a mechanical shutter is used when shooting with a slow shutter speed, the front and rear shutter curtains are so close to each other that only a fragment (strip) of the matrix is exposed at a particular moment in time. This helps reduce the distortion of the shutter.

Increase Flash Sync Speed
Synchronization of the flash using mechanical closures is often faster than in the case of electronic ones. This is due to the features of the electronic shutter and the scanning frequency of the matrix. When shooting outdoors in bright lighting and using the highest flash sync speed, it's best to work with a mechanical shutter. For example, the maximum sync speed of a flash when using a mechanical shutter Nikon 1 V3 is 1/250 s, and when using an electronic shutter - 1/60 s.

Did you like the article? Ask questions and do not forget

One of the main mechanisms of digital cameras is the shutter, its functional purpose is to skip, by clicking on the button, light rays to the matrix, which is a photosensitive element. Light rays are passed for a certain period of time. This period of time, during which the shutter opens, is called " excerpt". A feature of digital devices is the installation of closures that can be closed and opened at a very high speed, due to this the exposure time (illumination of the matrix) is regulated with high accuracy. For professionals it is very important that the photographic equipment has such accuracy, as well as a large range. When the exposure time is longer, more light enters the matrix. The shutter of modern digital cameras, especially for professional use, can effectively control the shutter speed. At the same time, this element protects the matrix from exposure, which can occur when reading the image, at the very beginning of the exposure.

Types of closures

The closures can have differences in their design, as well as in principle of closure. These features separate these elements into electronic and mechanical ones. AT different models digital camera is installed electronic shutter, it is built directly into the camera sensor.

Electronic shutter

At the right time, it turns on the sensor to receive a light stream, then switches it off at the command of the processor. The work of such a shutter is controlled by the camera's processor, its electronic equipment. When using such an electronic element on the matrix, the light flux falls constantly, due to this the image from the matrix is transferred to the LCD display of the digital apparatus. This image is read in a certain time, which lasts between zeroing the matrix and the moment when electronic information is read. This time also constitutes the exposure value, which is characterized by the camera. Thanks to electronic shutters, the photographer can use short exposures, even up to 1 / 15000s. The operation of the electronic shutter is distinguished by the absence of noise and vibration. The only thing, when using such a shutter, you can observe a low quality of the image, since the reading of the cells of the matrix occurs sequentially. In order to avoid image distortion, such unpleasant effects as halo, blooming, professional photo equipment are also provided with a mechanical shutter.

Mechanical shutter

Provides additional protection of the matrix against the ingress of fine dirt and dust. It also performs an important function, such as dosing light on the photosensitive element of the camera, that is, on the matrix. Thanks to the mechanical shutter, the expensive matrix retains its high technical qualities. For such a shutter is characterized by a certain period of service.
Mechanical shutters are also divided into two groups - curtain and central.

Center Shutter

Represents a construction of thin plates ( petals), opening to the edges and closing in the opposite direction, so the light flux is distributed evenly. It is installed between the lens of the lens. The most valuable for professionals have those closures, in which the flaps open very quickly.

Curtains

Have higher speed and more instant exposure. In the design of the curtain, two parts (curtains) are used, which are separated by a slit. It receives light from the lens. When the slit shutter is triggered, its first curtain opens the frame window, the second closes. The amount of exposure depends on the width of the gap that forms between the curtains. The principle of the shutter curtain, in which the curtains move, may distort some of the objects in the picture. But this shutter provides processing of short exposures and has a high coefficient of action.

Electron-optical shutter

In digital cameras, an electron-optical shutter can also be used, which is a liquid crystal located between two polarized plates. Through this crystal flows a light stream, then it falls on the optical converter.
Shutter is an important element in the operation of any photo equipment. The basic principle of any kind of shutters is opening during photography, skipping light rays. When the light flux hits the photosensitive element, the frame is exposed. The next step is to close the shutter, which allows you to proceed to the next shot. The shutter plays a very important role in the design of the camera. .