Currently, there are three types of cameras: compact, SLR and mirrorless. The first of them are the simplest, and the mirror ones, on the contrary, are considered the most advanced. If you decide to seriously take up photography, then you should opt for the "mirrorless" or "DSLR" options.
In the framework of this article, let's talk about the principles of operation and the device of a SLR camera. It makes no sense to know these parameters thoroughly, but it is necessary to have a general idea of \u200b\u200bthe methods of its work. This will allow you to look at the device from the other side, in order to thoroughly understand how to properly take a high-quality and original photo.
A bit of history
The invention of the camera was carried out in 1861. The goal was to acquire and store still images. Initially, in devices, these images were recorded on special plates, later - already on film for the camera. Around the 70s of the 20th century, digital technology appeared. Classic film cameras are a thing of the past. Today you rarely see them. They are almostcompletely superseded by digital technologies that allow you to get very high-quality images. SLR cameras are the most widely used and are recommended for professional photography.
Advantages and disadvantages
The advantages of the SLR as well as the disadvantages are shown in the following table.
| Benefits | Flaws |
| Shooting dynamic processes, that is, in motion | Cameras are technically difficult |
| Long battery life | The body is quite large |
| Impressive looks are more ergonomic | Mobility of components reduces reliability |
| The optics park is huge | Unable to view frame with slow shutter speed |
| Phase sensors of cameras provide high-quality and fast work | Manual mode is difficult to operate |
Working principle
A very simplified scheme of how a professional SLR camera works can be represented as follows:
- shutter opening occurs after we press the button. In this process, the light that is reflected from the object enters the machine through the lens;
- thus a picture is formed on the photosensitive element (matrix), photography takes place;
- shutter closes, then you can donew shots.
This process takes place in a fraction of a second. However, different models have different process characteristics.
The image is available for viewing on the screen immediately, which is very convenient for the photographer. Then it is saved on the computer for further storage and viewing or printing on photo paper.
Basic elements
The SLR camera is one of the more advanced designs. It has a number of functionalities. The main elements of the SLR camera device can be called:
- lens;
- matrix;
- aperture;
- shutter;
- pentaprism;
- viewfinder;
- turning and auxiliary mirrors;
- lightproof housing.
A visual diagram is shown in the figure below.
Lens
Let's consider what a camera lens consists of.
Under the lens understand a special system of optics, which consists of lenses located inside the frame. They can be made of either glass (for expensive models) or plastic (for cheap models). A stream of light passes through the lenses. He breaks. Thus, an image is formed on the matrix of the device itself. In the case when we are dealing with an expensive and good lens, you can get high-quality photos with increased sharpness and clarity in the absence of various distortions.
Main lens specifications:
- aperture shows how they relate to each otherthe brightness of the photographed object and the illumination of the image;
- focal length is reflected in millimeters from the optical center to the very focus where the matrix is located. The viewing angle depends on this parameter;
- zoom - the ability to zoom in on a distant object;
- a kind of mount.
Sometimes a wide-angle lens is used for SLR cameras. Such wide-angle cameras can be used to capture images of nature, landscapes. The pictures are voluminous and colorful. These lenses have focal lengths ranging from 24mm to 40mm.
Aperture functions
The aperture of a camera lens is a mechanism that is designed to regulate the flow of light projected onto the matrix. Its location: between the lenses in the device itself. Structurally, it consists of a set of overlapping petals (from 2 to 20 pieces), which can have a different shape. The magnitude of their mutual shift determines the size of the resulting hole. In this way, it is possible to change the amount of light that enters.
The size of the aperture determines the depth of field of the imaged space: the smaller the size of the circle, the greater the depth of field.
Currently, SLR cameras are equipped with jump type irises. They are ways to close to the set value only at the very moment of shooting.
Mirror work
The light that has passed through the diaphragm hole falls on the mirror. Next comes the divisionflow into two parts. One of them goes to phase sensors (reflected from the auxiliary mirror), which are designed to determine whether the image is in focus. Next, the focusing system commands the lens to move. In this case, they become such that the object comes into focus. This setting is called phase detection autofocus. In order to see the mirror in the body of the device, you just need to remove the optics. This is one of the main advantages of DSLRs over mirrorless digital cameras.
The second stream falls on the focusing screen. With this, the photographer is able to assess the depth of field of the future picture, as well as the accuracy of focusing. The convex lens, which is located above the focusing screen, increases the size of the resulting image. The mirror disappears when you press the shutter button, allowing light to seep into the matrix without obstruction.
Pentaprism and viewfinder
The stream of light that passes through the focusing screen enters the pentaprism. The latter has two mirrors in its composition. First, the image from the swivel mirror is upside down. The pentaprism mirrors flip it over, giving the viewfinder the final image in its normal form.
The viewfinder is a device that allows the photographer to evaluate shots in advance. Its main features can be called:
- lightness (formed depending on the quality and light-transmitting parameters of the glass from which it is made);
- size (area);
- coating (thisthe figure for today is 96-100%.
SLR cameras can be equipped with the following types of viewfinders:
- optical;
- electronic;
- mirrored.
Optical options are more common. Such devices are located near the objective lens system. Their advantage is the lack of power consumption, and the disadvantage is some distortion of the image that enters the frame.
Electronic devices are a small liquid crystal display (LCD). The picture is transmitted from the matrix of the camera itself to it. This type can be used even in strong sunlight, as it is located inside the case. However, it consumes electricity during operation.
Reflex viewfinders are considered the best, as they are able to provide the highest contrast, the quality of the outlines of objects. Similar devices are being transferred to digital photographic devices from analog films. The image seen by the photographer is created by a pivoting mirror.
Matrix: the basics of work
The matrix of a professional SLR camera is an analog or digital-analog system with photosensors. The latter are photosensitive elements that convert light energy into an electrical charge (proportional to the brightness of the light). As a result, the matrix converts the optical image into an analog signal (or digital). Then they pass through the converter - a microprocessor or a memory card.
The main features of the matrixare:
- permission;
- size;
- light sensitivity (ISO);
- relationship between signal and noise.
In SLR photography, two types of matrices have gained popularity:
- full frame (same size as 35mm camera film);
- truncated (diagonal reduced).
Matrices differ in the following formats:
- Full Frame - full frame (35×24 mm);
- APS-H - matrices for professional cameras (29×19-24×16 mm);
- APS-C - used in consumer product models (23×15-18×12 mm).
SLR basics
In general, the device itself consists of two parts: a camera (sometimes called a carcass or camera body) and a lens. The carcass with the lens looks like this.
Next, we present a schematic representation of the device. It reflects the structure "in section". In the figure below, under the numbers, the main components of the camera are indicated.
Characteristics of the main symbols in the photo:
- An object is a set of lenses capable of transmitting light, thereby forming an image.
- Inside the object itself is a diaphragm, which is a set of petals superimposed on each other in such a way that a round hole is formed.
- The area of this circle will depend on how far the petals will be moved from the initial position. It turns out thatThe aperture is used to control the amount of light that is let through. She has the ability to open and close. If it is completely closed, then the area of the hole is minimal and the light penetration is also at a minimum. If it is open, then the picture is reversed.
- Next, the light that has passed through the aperture hits the translucent mirror number 3. If you remove the lens, the very first thing we see inside will be just the mirror. On it there is a division of the stream of light into two parts.
- The first half of the light stream then enters the focusing system at number 4. This system is nothing more than several phase sensors that determine the fact that the image is in focus. These elements create a task to move the lenses in such a way that in the end the desired object is in focus.
- The next part of the light stream moves to the focusing screen 5. It allows you to evaluate the accuracy of the focus and determine what the depth of field will be in the final image.
- Further after the focusing screen, the light enters the pentaprism in the camera. The picture that goes from lens 1 to mirror 3 is upside down. The pentaprism in the camera consists of two special mirrors that flip the image so that it takes a normal position in the viewfinder.
- Further from the pentaprism, the light moves into the viewfinder, where you can see the final image (not upside down). The main characteristics of the viewfinder: coverage, size, lightness. Currently, in advanced cameras, its coverage is about 96-100%. If it is less than 100%, thenin such a situation, the photograph turns out to be a little larger than the photographer himself can see. However, this deviation is insignificant. If the resolution of the matrix is high, then all unnecessary can be removed. The size of the viewfinder is determined by its area. Its lordship is determined by its quality and the light transmission of the glass. By increasing the size of the viewfinder and increasing the lightness of the lenses, it becomes easier for the photographer to focus and determine whether the subject is in focus. It brings great pleasure to any photographer to work with such devices. However, their installation is possible, as a rule, only in top-end cameras, as well as in those that are above the average price level. After the camera and all its parameters are fully configured, the photographer presses the shutter button. At the moment, the mirror is raised and the light flux hits the most important element of the device - the matrix.
- In the figure, the mirror rises, shutter 1 opens. In mirror devices, the shutter is mechanical and determines the time it arrives at matrix 2. This period of time is called shutter speed (or exposure time of the matrix). The main characteristics of a shutter are as follows: lag and speed. With the help of the log, you can determine how quickly the shutter curtains open after the shutter is pressed. The smaller this lag, the higher the likelihood that a passing car will be captured in a photo with high quality. As a rule, SLR cameras have a small shutter lag. It is measured in milliseconds. Shutter speed refers to the minimum time it takes to open the shutter.which means the minimum exposure. If you take a budget camera, then this value is 1/4000 s. If you take an expensive one, then the time will be already 1/8000 s. When the mirror is raised, the light does not get anywhere, but moves directly to the matrix. For example, in a situation where we use a SLR camera, when photographing we look through the viewfinder all the time, then after pressing the shutter button, the first thing we see is a black spot. This time is determined by the exposure. If you set the shutter speed to 5 seconds after pressing the shutter, a black spot will be observed for the same time. After the matrix of the SLR camera is exposed, the mirror will return to its original position, and the light will again enter the viewfinder. Thus, there are two main elements that regulate the amount of light that hits the sensor. The first one is aperture 2. It determines the amount of light. which is skipped. The second is the shutter, which controls the shutter speed, or the period of time during which light is able to hit the matrix. It is these two mechanisms that underlie the functioning of a SLR camera. The effect of the photographing process depends on how they are combined. It is important for the photographer to understand their meaning.
- Matrix 2 can be represented as a microcircuit with photosensitive elements (photodiodes), which have the ability to respond to light. A light filter is installed in front of the matrix in the camera, which is responsible for obtaining a color picture. Important characteristics of the matrix: size and signal-to-noise ratio. The higher these parameters, the better for quality.photos.
After the matrix, the image goes to the ADC converter, from where it moves to the processor. Further processed and saved to the memory card.
Another essential detail of a SLR camera is the aperture repeater. Focusing is done with a completely open aperture. When a closed aperture is set in the camera settings, the photographer will not see any changes in the viewfinder. In order to see how the frame will come out, you can press the button. In this case, the aperture opens to the set value, the changes can be seen.
Basic Modes
Camera modes are generally grouped into the following four areas:
- automatic, in which the camera itself determines all the settings;
- portrait is used for shooting people and allows you to maximize the volume by blurring the background;
- landscape mode maximizes depth of field for excellent clarity;
- macro mode allows you to zoom in with focus on the subject;
- sport mode is suitable for shooting sports and moving subjects;
- night portrait for shooting in dimly lit places with flash;
- software auto P allows you to set the white balance, matrix sensitivity, jpeg settings. Used when there is no time for manual settings;
- shutter priority mode S, in which the photographer sets the shutter speed and the camera sets the aperture. Applied when neededemphasize movement in the frame;
- Aperture priority mode A allows you to set the aperture value, and the camera selects the shutter speed. Used when taking a portrait;
- manual mode M: all parameters are set by the photographer himself. Ideal for night shooting and studio photography.
Canon DSLR
Reflex cameras "Canon" are manufactured by the world market leader in video and photo equipment. The logo of this company is used on all amateur and professional devices. For almost a century of its own history, the company has established professionalism in work, releasing one of the best models of cameras. Among the widest range, each user can find a camera according to their preferences.
Canon in the market of modern electronics is one of the flagships in terms of the production of photographic equipment. It is the most advanced manufacturer in the development of SLR cameras. A wide range allows you to choose a suitable model. The company's products are always characterized by high quality workmanship and good assembly of Canon SLR cameras. This company has developed a series of Electronic Optical System (EOS) - SLR cameras with auto focus.
Conclusion
The cameras studied in this article allow you to take high-quality pictures thanks to the large matrix in the device of a SLR camera. That is why theyused in their work by professional photographers and amateurs who are seriously involved in photography. Interchangeable lenses are also an important factor in the popularity of SLR photographic equipment.
