What is exposure? This is the product of the illumination of the photosensitive layer of the matrix by the time during which the light acts on this layer. It is expressed in lx×s (lux per second). This is the amount of light hitting the matrix.
Illumination of the matrix is regulated by a diaphragm, the time of exposure to light - exposure. There is also a third parameter - ISO, which determines the sensitivity of the matrix. The higher the sensitivity, the lower the exposure required. These three parameters - aperture, shutter speed and ISO, are interconnected by a ratio called exposure triangle.
Normal exposure should be such that the sensor, at a given sensitivity, receives enough light to register an image with a proportional reproduction of the original brightness levels, that is, ideally, it should be as we see it, without dips in the shadows and without highlights. plots.
If the image turns out too dark in relation to the actual scene being shot, details in dark areas disappear on it, then such an exposure is called insufficient, and the image itself is called underexposed or underexposed. Simply put, too little light fell on the matrix to properly capture the image.
If the image is too bright compared to the scene or subject being shot, details in the bright areas disappear on it, then such an exposure will be excessive, and the image will be called overexposed or overexposed. In this case, too much light fell on the matrix, so the matrix is not able to correctly convey the range of brightness.
The shutter speed and aperture value required to obtain a normal exposure is called expocouple . To obtain the same exposure, you can use different combinations of shutter speed and aperture, that is, different exposure pairs. I will give an example: the values of the shutter speed-aperture pairs are 1/500 f / 5.6; 1/250 f/8; 1/125 f/11; 1/60 f/16 will give the same exposure. This is true if the ISO value does not change. If you also change the ISO value, then you will no longer get an expopara, but an "expotroika", but this name is not generally accepted, but the term is used exposure triangle.
How to practically use this same triangle? Everything is very simple. If we change any one value, for example, the aperture, then the triangle is out of balance. To restore balance, you need to change any of the remaining two options, such as shutter speed or ISO (or both). It is better not to change the ISO parameter unless it is absolutely necessary, but to use its minimum value. Elevated ISO values lead to digital noise in the image, and this degrades the image quality.
Once you understand and feel in practice the connection between these three parameters: aperture, shutter speed and ISO, setting the correct exposure will no longer be a difficult task for you and you can easily adjust it for the most complex scene.
To learn how to take clear, eye-catching pictures with a camera with semi-automatic or manual shooting settings, you need to understand the basics of the photographic process. Main concern good photographer- choosing the right exposure, otherwise beautiful shots will not work. Three interrelated exposure settings in the hands of a skilled photographer turn into effective artistic tools.
The concept of exposure in a camera means the amount of light that hits the sensor (matrix) at the time of shooting. The clarity and brightness of objects in the photograph depend on the correctly set values of the shooting parameters.
If there is not enough light on the matrix, then the photo is darkened. In this case, we say that the exposure was chosen small. With a large amount of light flux, on the contrary, the image is very bright. Then they talk about choosing an unreasonably large value. In both cases, there are no halftones in the images, the quality of such photographs suffers.
Modern digital photographic equipment is equipped with a number of automatic modes and manual exposure setting. For novice users, it is important to understand the principles of manual adjustment, to learn how to use the histogram, which makes it clear how evenly the light is distributed over the frame.
Parameter relationship
Shooting parameters in the camera are adjusted in three interdependent directions: aperture, shutter speed and sensitivity (ISO). It is important for a photographer to understand the relationship between these values set on the camera, their influence on each other.
- Diaphragm is a mechanically adjustable "pupil" of the lens and is responsible for the intensity of the light supply. By varying the value of this parameter, you can change the intensity of the light flux falling on the camera matrix.
- Excerpt characterizes the time period of light exposure to the matrix with the shutter open. The picture is brighter with a slow shutter speed.
- ISO value determines the degree of susceptibility of the matrix elements to light.
Graphically, the relationship of these parameters is represented as a triangle.
Most modern digital cameras have exposure program mode. When the automatically set exposure pair does not satisfy (the frame is a little darker in the user's eyes or, on the contrary, a little lighter), you can make an exposure correction. The frame histogram will help you understand in which direction to correct.
Using the Histogram in Exposure Evaluation
A histogram is a graphical representation of the dynamic range of light distribution across a frame. The graph shows the brightness and contrast levels of an image.
The horizontal axis of the graph reflects smooth tonal transitions from dark to light details. The vertical represents the quantitative characteristics of a certain tone. The histogram is read from left to right. The size and shape of the graph determines the contrast of the frame, the correct choice of exposure.
Advice! You can view the histogram for estimating exposure on the camera during Live View shooting (icon)
Let us give examples of graphs with no halftones.
Exposure compensation is performed by moving the adjustment slider to 0.
Important! The mechanism for implementing this process may differ for different models, so it is advisable to study the instructions for a particular model.
Exposure scale and bracketing in photography
To use effectively reflex camera, it is important to understand concepts such as scale and exposure bracketing. The exposure scale is used in all models of photographic equipment with support for semi-automatic and manual adjustment of shooting parameters. This is the same slider that shows the level of customization. The optimum level is zero value.
You can save time on the selection of optimal shooting parameters using bracketing.
The essence of the method is to sequentially shoot several frames (from 3 or more) with different exposure values. Pictures are taken in succession with zero exposure compensation and symmetrical values on the scale in the plus and minus directions. The photographer will be able to choose more successful shots later.
Reception is relevant when shooting in low light conditions, when it is difficult to find the optimal shooting parameters. Professional cameras, premium DSLRs are usually equipped with manual exposure bracketing functionality. Budget-class digital technology has built-in AEB mode, which allows you to take a series of pictures with a set correction step with a single press of the shutter button.
Exposure metering mechanism
Metering is carried out according to one of three algorithms.
- Integral, which is also a matrix measurement of parameters, is performed over the entire matrix, and the data are averaged. The aperture and shutter speed values set by the program are the arithmetic average of the parameters.
- Spot metering is produced in a small area in the center of the frame, and the illumination at the edges of the matrix does not affect the calculated values of aperture and shutter speed.
- Weighted average determines the exposure parameters according to a weighted principle: the calculation is most influenced by the central and nearest points to the center of the frame.
Advice! Which metering mode to choose depends on the shooting conditions. If the illumination in the frame is relatively uniform, the objects do not stand out from the general tonality, then it is recommended to set the exposure pair using matrix metering. For portrait photography, the other two methods are more suitable.
Each exposure metering mechanism has its own icon.
In order to manually set the exposure pair correctly, it is important to understand the EV values in the camera. Far from everyone knows what concept lies behind the abbreviation EV. The abbreviation stands for "Exposure Value", which translates into Russian "exposure value». The concept of "Exposure Value" determines the illumination by which the exposure pair is set. A different EV value is recommended for each sensor sensitivity setting (the value varies depending on shooting conditions). Tables of recommended EV values can be found in the instructions and thematic literature. Having understood the relationship of exposure parameters, the owner digital camera will be able to creatively approach the shooting process.
The concept of exposure in the practice of photography is important. All professional photographers and some beginners know and understand this term. Hence, they produce high-quality images.
Exposure is the amount of light that passes through the aperture and hits the camera's sensor to form an image. Exposure has a direct effect on the brightness of objects.
If the exposure is low (not enough light), the picture will be dark. With a large exposure (when there is too much light), the picture will be too bright. In both cases, the snapshot will be corrupted, i.e. some midtones will be lost and the photo will be of poor quality.
IMPORTANT: Exposure only affects the brightness of the image, nothing more. Color or sharpness is adjusted separately.
It is clear that the exposure is quite an important parameter, but why so much attention is paid to its setting. The fact is that the dynamic range of the camera matrix is limited. It is responsible for the ability to capture both dark and bright objects at the same time. In the dark or light areas of the picture, the wrong exposure will corny lead to loss of detail in the frame.
Setting the exposure on the camera
Beginning photographers tend to take pictures in automatic mode. It's simple, here the exposure adjusts itself, depending on the general lighting. In automatic mode, it is convenient to take photos of non-moving objects in good light.
However, to get creative shots, you often have to resort to manual settings. First of all, you need to know that the exposure depends on:
- excerpts;
- diaphragms;
- Sensitivity.
Excerpt determines the amount of time at which the aperture is open. Therefore, during all this time, the light will enter the matrix through the lens. Exposure can last milliseconds or tens of seconds (even minutes).
Diaphragm A hole in the lens through which light passes. This hole is adjustable and can vary in size.
Thanks to these two parameters separately, it is possible to measure the amount of light falling directly on the matrix. Essentially, we are measuring exposure. But at the same time, you need to understand that both aperture and shutter speed are also important parameters in themselves. The aperture determines the sharpness of the background, the shutter speed plays extremely important role when shooting dynamic scenes. So you have to change these parameters depending on the plot, but at the same time you need to select them without compromising exposure.
In principle, it sounds complicated, although in fact everything is simple: first, one of the parameters (aperture or shutter speed) is selected for a specific scene and effect in the picture, and then the second parameter is selected to obtain the correct exposure (so that the brightness is optimal).
Below is a table with which you can easily adjust the exposure.
Diagonally, it is easy to see that there are cells of the same color, which means the same exposure. If you change the shutter speed or aperture, another setting is easy to find at the intersection of rows or columns of the same color.
Example: for the correct exposure for a particular lighting, choose a shutter speed of 1/15 sec, aperture - 8.0. If you change the shutter speed to 1/60, then you need to set the aperture to 4.0 to maintain the correct exposure.
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How to explain in a nutshell what exposure is? Today, with a similar question, one colleague puzzled me. Most of the explanations for the concept of exposure found on the net are full of technical terms, each of which requires a separate explanation. And the description from Wikipedia is generally capable of blowing up the brain of an unprepared reader.
Therefore, the task of this note is to try to “in a nutshell”, in a simple way, explain what an exposure and expopara are.
For beginners, the word "exposure" often confuses, although in fact everything is quite simple. And you need to deal with it, because otherwise you simply will not be able to move forward as a photographer.
Is your photo too dark or too light? So the exposure is wrong.
What does the camera do when you press the shutter? It transmits a certain amount of light through the lens to the matrix. Or on tape, if you like. Roughly speaking, exposure is the amount of light that hits your camera's sensor.
A combination of two parameters is responsible for this amount of light - the “f” number (aperture) and shutter speed. This is the Expopara. Why the combination?
For example, let's take combinations of f/4 and 1/25s, f/6.3 and 1/10s, f/8 and 1/6s. The values are different, but the exposure will be the same. Why? Because the total amount of light hitting the matrix will be the same. And the resulting image is properly exposed.
Let me explain with a real life example. You need to get 1kg of a mixture of two components. Flour and sugar. If you mix 300g of flour and 700g of sugar, you will get 1kg of mixture. But if you mix 200g of sugar and 800g of flour, you will still get the same 1kg of mixture. So it is with exposure.
Exposure is the amount of water poured into a barrel. The barrel can be empty, half full or top of the line. Then shutter speed is the time that we pour water into the barrel through a hole called a diaphragm.
Well, when the barrel is half full, that's the correct exposure. But in order to fill the barrel halfway, we can make the pouring hole larger (diaphragm open), then it will take quite a bit of time to fill the barrel to the desired amount of water. And you can do the opposite, make a small hole and increase the time.
Light (color) sensors in modern digital cameras they are just such "barrels" into which light is "poured".
If the exposure is wrong, you will constantly get either too light or too dark a frame.
The question arises, why then different values of shutter speed and aperture, if the exposure is the same?
Let's go back to the flour and sugar example. The final weight of the mixture will be the same, but the final taste of the dish will be very different.
So it is in photography. Proper exposure is more of a technical component of high-quality photography. But the values of shutter speed and aperture - for artistic.
Look at the example below.
values are different - the exposure is the same
And on that and on the other frame, the exposure is the same, but the aperture and shutter speed values are different, and we also got a different effect.
Why is that? On the first frame, the aperture is open to let in a lot of light, therefore, in order not to “light up” the frame, you need to set a very fast shutter speed, thereby limiting the excess light. The result is frozen frozen water. On the second, the aperture is extremely clamped, passing a meager amount of light. To compensate for this, you need to increase the shutter speed (the time during which the shutter is open). The result is viscous blurry water that managed to "leak" in the frame in 1/4 second.
That is, summarizing the explanation in a nutshell.
The correct exposure is when we have chosen the optimal combination of shutter speed and aperture, at which a sufficient amount of light has hit the matrix. Not too much, not too little.
EXPOSITION EXPOSITION (from the Latin expositio - presentation, description), selection and placement of exhibits according to a certain principle (thematic, chronological, etc.) in museums, at exhibitions.
Modern Encyclopedia. 2000 .
Synonyms:See what "EXPOSURE" is in other dictionaries:
exposition- and, well. exposition f., German. Exposition lat. expositio presentation, description. 1. Placement in a certain system of items exhibited for viewing. New exposition Exhibitions. BAS 1. || A collection of exhibited items located in ... ... Historical Dictionary of Gallicisms of the Russian Language
- (lat.). exposition, explanation, exposition. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. EXPOSURE 1) exposure to light; 2) holding before photographic. objects removed by the device. Dictionary of foreign ... ... Dictionary of foreign words of the Russian language
EXPOSITION, exposition, female. (lat. expositio). 1. The introductory part of a literary or musical work, containing motifs that are developed in the future (lit., music). 2. Arrangement, layout, hanging, etc. items, ... ... Explanatory Dictionary of Ushakov
- (amount of illumination, light exposure), surface density of light energy: the ratio of light energy dQ incident on a surface element dA to the area of this element. Equivalent definition of the product of illumination E by ... ... Physical Encyclopedia
Placement, exposure, prologue, illumination, irradiation, exhibition, exposure, exposure, position, location Dictionary of Russian synonyms. exposition excerpt Dictionary of synonyms of the Russian language. Practical guide. M.: Russian language. Z. E... Synonym dictionary
- (from Latin expositio, display, presentation), placement in exhibition and museum premises or in the open air according to a certain system of various works of art, monuments of material culture, historical ... ... Art Encyclopedia
EXPOSURE- (1) the photographic amount of illumination imparted to the photosensitive material in photography and filming millions of prints; exposure value is determined (see); (2) E. energy radiation energy per unit surface area ... ... Great Polytechnic Encyclopedia
exposition- (from Latin expositio exposition, description) external, semi-quantitative and quantitative assessment of the concentration, frequency and duration of exposure to a substance on the body. Ecological encyclopedic dictionary. Chisinau: The main edition of the Moldavian ... ... Ecological dictionary
exposition- The process by which radiation is recorded on an imaging system. [System non-destructive testing. Types (methods) and technology of non-destructive testing. Terms and definitions (reference guide). Moscow 2003] exposition Parameter ... Technical Translator's Handbook
exposition- Orientation of mountain slopes and any forms of relief in relation to the cardinal points and to the prevailing air currents. Syn.: slope exposure… Geography Dictionary
Books
- Exposure. Practical guide. A Simple and Effective System for Selecting the Ideal Exposure by Michael Freeman. Exposure. Practical guide. A simple and effective system for choosing the perfect exposure for your photo - in any conditions and in any light. In this book: Simple and effective...