Depth of field calculator. how to calculate flu Options for not quite correct and correct comparisons of cameras

Depth of field in photography– this is the distance between the front and rear boundaries of the sharply depicted space ( in optical image space), measured along the optical axis, within which the subjects in the image appear sharp (Fig. 1).

Rice. 1 - Depth of field

There is also the concept of “depth of field” (DOF), which is often confused with the concept of “depth of field”.

DOF- this is also the distance along the optical axis of the lens, but it lies in the space of objects and within which objects will be depicted sharply. (Fig. 2, 3).

It is the result of a depth of field selected by the photographer, which is visible directly in the photograph, i.e. in the plane of optical images behind the lens. The depth of field is located in the plane of the depicted objects. This is the main difference.

DOF is affected by:

• distance to the subject;
• lens focal length;
• lens size.

Rice. 4 - Changing the depth of field at different focal lengths and aperture values

Maximum depth of field

Some photographs, such as landscapes, require a greater depth of field to capture as much of the scene as possible.

To do this you need:

• stand so that foreground objects are as far as possible from the lens, move away to the maximum possible distance;
• close the aperture to the required value (f11 - f22), checking the depth of field with the aperture repeater;
• If possible, use a wide-angle lens.

Some cameras have an automatic exposure metering mode with depth of field control - DEP. In this case, you need to specify two points that should be displayed sharply and shoot. The shutter speed and aperture values ​​will be determined automatically. The method works when the lens autofocuses.

To achieve an infinite (to the horizon) depth of field, use hyperfocal distance– the distance from which to infinity objects look sharp with a lens focused at infinity (Fig. 5). With DOF, it starts from 1/2 the distance to the focusing point and to infinity (Fig. 6).

The hyperfocal distance values ​​for given parameters (lens focal length, aperture number, distance and lens circle of confusion) are calculated using special programs or tables, for example, Table 1.

Table 1 - Calculation of depth of field and hyperfocal distance values

Minimum depth of field

The task of minimizing depth of field is much more difficult than maximizing it. In many cameras (mostly compact ones) this is practically impossible due to the small size of the sensor, the default short throw lens and focusing by searching for the hyperfocal distance. This is precisely one of the strongest arguments in favor of a digital SLR camera - the ability to sharpen the part of the scene that the photographer needs.

Blurring the background or some foreground elements allows you to focus the viewer’s attention on the main subject of photography, highlight it, and is one of the key creative moments and the cause of the phenomenon (Fig. 8, 8).

To achieve a minimum depth of field you can:

• use the maximum open aperture (f1.2 - f1.8, f2.8) depending on the lens;
• use long telephoto lenses. The longer the focal length, the shallower the depth of field in the image;
• get as close to the subject as possible;
• If possible, increase the distance between the background and the subject.

Degree of lack of sharpness

The amount of image blur varies smoothly along the depth of field. An object is depicted as absolutely sharp only in the plane of focus; all other points begin to gradually blur as they move away from this plane.

To achieve this depth of field, a macro lens was used with the aperture wide open. The shooting was carried out from a tripod as close as possible to the object - the “5 kopeks” coin.

Difficulties related to depth of field

Often, when using long-focus or macro lenses (long distances or macro photography), a situation arises when it is impossible to ensure such a depth of field that all significant elements are sharp, since the depth of field is several millimeters. This may also be due to the problem of poor lighting, since in this case it is necessary to use open apertures to provide the necessary .

To solve such problems you can:

• choose a viewing angle such that the change in depth of field is minimal (Fig. 11);
• remove from a stop (tripod, monopod);
• when photographing people, focus on the eyes, since we are used to paying attention to them first;
• in macro photography, a series of frames is taken with the camera itself shifted (without changing the focus), which are then combined into one.

Bottom line

Adjusting the depth of field during shooting occurs mainly by changing the aperture value and the distance to the subject.

In landscape photography, the maximum depth of field is used, which is achieved by focusing at the hyperfocal distance, which is calculated using special tables or calculators.

In portrait photography, the depth of field is limited to such that it allows you to highlight the necessary elements. It's best to focus on your eyes. An exception may be documentary filming, when you need to show a person in his environment, which should be clearly recognizable (sharp).

When shooting macro, sports, or wildlife with long lenses, photographers may experience insufficient depth of field. To do this, close the aperture to possible values ​​(f4-8) within the required exposure.

DOF (depth of field) calculators are one of the most popular types of software designed to provide the photographer with specific information about shooting parameters and make it easier to obtain high-quality images. There are a lot of different implementations of depth of field calculators on the Internet, but the one created by Polish photographer and programmer Michael Bemowski is without a doubt one of the best.

The Bemovsky calculator has many settings, adjustable parameters, fixed presets and saved configurations. It not only calculates parameters numerically, but also visualizes the results in a visual form.

First of all, you can set specific shooting parameters - lens focal length and matrix size, aperture, distance to the subject and to the background. By the way, these very objects and backgrounds are also customizable - selected from several proposed options.

As you play with the shooting parameters, the visualization (the image in the window on the right) works out in real time all the changes you make.

Even background blur (bokeh) is simulated, the degree of this blur corresponds to the parameters entered (and calculated) at the moment.

At the bottom of the page there is the actual depth of field calculator, which calculates the location and depth of the field of focus and presents the results in a visual way.

If you are visiting the site from a mobile phone, clicking the button in the upper left corner will change the interface to the “mobile” option. The application does not require a connection to the server to work, so the author also offers an offline version that you can download to your computer. The entire project is completely free and relies on advertising and donations.

In our opinion, the calculator has not only (and not even so much) serious practical significance, but, first of all, educational value. We recommend that beginning photographers thoughtfully play with the settings, and perhaps return to this activity more than once in order to better understand and feel what lens to take, what aperture to set, whether to approach the subject closer or further - in order to get the desired result, as with from the point of view of depth of field and bokeh, as well as the ratio of the scales of the object and the background.

Publication date: 20.02.2015

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From the previous article, you already know what depth of field is and what parameters it depends on. Today we will get acquainted with this concept in more detail. How to accurately calculate depth of field? How to achieve maximum depth of field, and why do depth of field calculator programs often make mistakes in their calculations? Read more about this.

NIKON D600 SETTINGS: ISO 125, F4, 1/80 sec, 200.0 mm equiv.

When should you worry about accurately calculating depth of field?

Very often, a photographer needs to sharpen certain objects and needs to achieve a certain depth of field. Therefore, he needs to calculate it accurately. Experience is experience, but it doesn’t always work one hundred percent. Accurate calculation is necessary in landscape, object, and macro photography, if you print photographs in large formats and their sharpness is fundamentally important. But if you shoot purely amateurishly, without worrying at all about the quality of photographs, and print pictures in small formats such as 10x15 cm, or are engaged in art photography under the motto “who said that pictures should be sharp?!”, then all this is for you not that important. An accurate calculation of the depth of field helped me get the most out of my camera equipment: after all, I didn’t buy an expensive multi-megapixel camera in order to not fully use its capabilities.

Formula for calculating depth of field

A long time ago, a formula was derived for calculating depth of field. In the last lesson, we already talked about the main criteria that affect the depth of field - focal length, focusing distance, aperture. All of them are presented in the formula.

• R1 - front boundary of the depth of field;
• R2 - rear boundary of the depth of field;
• R - focusing distance;
• ƒ - absolute focal length of the lens;
• K is the denominator value of the current relative aperture (aperture value);
• z is the diameter of the scattering circle. A very interesting parameter that fundamentally affects the calculation of depth of field. We will return to it more than once in this article.

Accordingly, the depth of field P will be calculated using the formula:

P = R1 - R2

Let’s not forget that the focusing distance, as well as the near and far edge of the depth of field, are measured not from the front lens of the lens, but from the place where the camera’s matrix is ​​located - from the focal plane.

Of course, in practice no one uses this formula today, but it is useful to know about its existence. It is on the basis of this formula that numerous depth of field calculator programs work, into which you can simply enter shooting parameters and find out the depth of field without any mathematical exercises. We will talk about these programs below.

What is considered sharp in a photograph? Circle of Dispersion

We already know that there is no clear boundary between sharp and unsharp areas of the frame. This knowledge will help us understand how the depth of field of the depicted space is generally formed. For simplicity, we will agree that we will photograph with a perfectly sharp lens dots of negligible diameter, laid out in a row.

Then the sharpness in the frame is distributed as follows:

Only the point that is exactly at the focusing distance of the lens will be ideally sharp. Points in front or behind the focusing distance will be blurred. In the resulting photograph, until a certain moment, this blur will not be noticeable to the eye of the observer. However, then the dots will begin to smoothly turn into small circles, and the observer will begin to notice blur in the frame. The minimum diameter of such a blurred circle, noticeable to the eye, was called the “circle of confusion” (in English - circle of confusion or abbreviated as COC). All points with a diameter smaller than the circle of dispersion are considered sharp in the photograph. All points with a large diameter are considered unsharp.

At what point does blur become noticeable to the eye? It all depends on the observer. Therefore, depth of field is a subjective value. A more keen and meticulous observer will have higher demands on the sharpness of the image than a less sophisticated one. But it's not just about the observer. Much here will depend on the resolution of the matrix (or film). As long as the scattering circle is smaller than the pixel size on the camera matrix, all points in the photo will be equally sharp. And of course, a lot depends on the observation conditions. If we look at a small photo, we will see less detail on it than on a large one. Based on all these premises, since the days of photographic film, the diameter of the circle of confusion has been 30 microns or 0.03 mm. Based on this value, manufacturers on some lenses make a depth of field scale like this:

A simple depth of field scale on the Nikon 50mm f/1.4D AF Nikkor lens. How to use it?

The scale shows the values ​​of apertures F11 and F16 with marks (highlighted in yellow), above them is a scale of focusing distances (highlighted in blue). When focusing at a certain distance, we will see what distances will be between the marks of the depth of field scale. They will say to what extent the depth of field will extend. It is worth mentioning that modern lenses use such a scale less and less often, since depth of field can only be estimated very roughly using it.

Calculator for calculating depth of field

Depth of field calculator (or DOF calculator in English) is a program that allows you to accurately calculate the depth of field without using complex formulas. Today there are several publicly available DOF calculators on the Internet. They are easy to find using an internet search.

However, calculators designed for smartphones have much greater practical use. After all, they can be used right at the moment of shooting, wherever it takes place. In the AppStore (for Apple iOS), Google Play (for Android OS) and WindowsPhone application stores, the search query “DOF Calculator” or “DOF Calculator” produces many applications. Most of them are quite workable: they all work according to the same formula described above. In a little more detail, I would like to highlight three free applications among the general mass, developed for different operating systems. In my subjective feeling, they are the most convenient to use.

We use depth of field rationally

When calculating the depth of field and using this data when shooting, it is important to consider that it extends in both directions from the focusing point. Often photographers forget about this, believing that depth of field extends only beyond the focal point. With this approach, the depth of field will be calculated incorrectly and sharpness at the rear edge of the subject will be lost.

In addition, in practice you will encounter the fact that the front and rear boundaries of the depth of field are located at different distances from the focusing point.

For example, when shooting a landscape and focusing on the foreground, you will definitely notice that most of the depth of field extends behind the focus point, and just a little in front of it. The general pattern is this: the further the focusing distance, the more the depth of field goes beyond the focusing point and extends less significantly in front of it.

In each specific case, the depth of field distribution parameters will be slightly different. So here we can give only one practical recommendation: every time you need to strictly calculate the depth of field, it is worth considering that the front and rear boundaries of the depth of field are at different distances from the focusing plane.

Why do depth of field calculators sometimes lie? Circle of Dispersion and modern realities

We often hear from users of the programs described above that the program displays data that does not correspond to reality. In the photo the depth of field is less than what the program showed. The whole problem is that depth of field calculators usually use a circle of dispersion parameter of 0.03 mm for calculations.

In the days of film photography, a value of 0.03 mm was quite enough: film did not have such high detail (resolution) as the matrices of modern cameras. The diameter of 0.03 mm is too large for modern devices. A circle with such a diameter will include quite a lot of pixels of the image obtained from a modern matrix, and therefore such a circle will be clearly visible in the photo.

As you can see, the circle of confusion with a diameter of 0.03 mm includes quite a lot of image pixels. This means that in the photo such a circle will no longer look like a dot, but rather a circle. And at the boundaries of the depth of field, the image will be noticeably less sharp. We obtained the area of ​​one pixel by simply dividing the area of ​​the matrix by the resolution of the images it produces. Of course, this is only a rough estimate: one pixel on the matrix does not give one point on the image: one pixel on the photograph is obtained by analyzing data from several pixels on the matrix at once. By the way, this is why pixel-by-pixel image detailing is impossible on modern matrices - the relationship between a point on the image and the physical pixels on the matrix is ​​too complex.

However, even such a rough assessment helps to understand the essence of the problem: film sharpness standards are now outdated and require adjustments. Especially if you use high-quality modern optics that provide high image detail. Especially if you shoot on cameras with APS-C or more compact matrices: the smaller the matrix, the smaller the size of one pixel (to fit them all in a given area), therefore even a small scattering circle will be noticeable. The same applies to multi-megapixel full-frame devices such as Nikon D810, Nikon D800 and Nikon D800E with 36 megapixels on board.

Today, to effectively calculate the depth of field, it is necessary to revise the diameter of the circle of confusion towards its reduction.

What does this look like in practice? When shooting this still life, I paid special attention to calculating the depth of field. So that the entire composition “from start to finish” is included in it. To calculate the depth of field, I used a circle diameter of 0.03 mm.

In theory, everything that is included in the depth of field zone should be equally sharp. But what picture will we see in reality?

How can this be? How to calculate depth of field without errors? To do this, when calculating depth of field, I recommend using a circle of confusion that is smaller than the diameter. Based on my subjective experience, I chose a diameter of 0.015 mm. It is no longer very rational to use a circle with a smaller diameter: it is unlikely that you will encounter such sharp optics that will shoot with such high detail. Of course, the smaller the diameter of the scattering circle we use in calculations, the smaller the depth of field we get. However, such a calculation will be more correct.

In the parameters of most depth of field calculators, the diameter of the scattering circle can be set manually. Take advantage of this opportunity! Note that if you are using not too sharp optics, for example, a hyperzoom lens, then you can safely use a circle of dispersion of 0.03 mm in the calculations, since the lens will not allow you to achieve greater sharpness.

It is also worth noting that, based on the above data, one may get the impression that in this case, compact cameras should be able to blur the background better and more strongly (and the blurred background is a consequence of a small depth of field): after all, they have very small matrices and there will be a large circle of dispersion on them noticeable even more. Let us disappoint: compacts use optics that are too short-focus, so the depth of field will still remain very significant, no matter what circle of dispersion we use in depth of field calculations.

We sharpen everything ad infinitum. Hyperfocal distance

Often you need to make sure that the entire frame, from beginning to end, is sharp. This is especially necessary in landscape, architectural, and interior photography. Focusing at infinity will not help: it will cause us to lose sharpness in the foreground. But often you want to sharply show both the foreground and a very distant background. To achieve maximum depth of field, starting as close to us as possible and covering infinitely distant objects, photographers use focusing on hyperfocal distance.

Hyperfocal distance- this is the distance, when focusing on which everything from ½ of this distance to infinity will fall into the depth of field.

The most difficult thing about hyperfocal distance is calculating it. But once you have calculated the hyperfocal distance, you can easily and quickly shoot any landscapes without prior focusing and calculating the depth of field, simply focusing the lens at the hyperfocal distance you already know. Like depth of field, hyperfocal distance will depend on the focal length of the lens and the aperture value. The shorter the focal length and the more closed the aperture, the closer the hyperfocal will be to us.

All the depth of field calculators described above can also calculate the hyperfocal distance. They are easy and convenient to use. When calculating the hyperfocal distance, the same remarks regarding the diameter of the circle of dispersion will be valid. It is especially convenient to aim at the hyperfocal distance when the lens is equipped with a focusing distance scale. Then you can simply manually set the scale to the desired distance, as I always do.

A wide-angle lens with a focusing distance scale is an excellent choice for landscape photography.

Practical difficulties in working with hyperfocal distance lie in the fact that the focusing distance scale, even on top modern lenses, is greatly reduced: it is small and only rough estimates of the focusing distance can be made from it. Whereas for absolutely accurate targeting of the hyperfocal distance, sometimes it is necessary to calculate the distance not only in meters, which the scale allows you to do, but also in centimeters.

Typical focusing distance scale for a wide-angle lens.

A wide-angle lens is perhaps the main tool of a landscape photographer. And it is when using a wide-angle that it mainly makes sense to use the hyperfocal distance. However, you can notice that on this scale there are no markings between “infinity” (and “infinity” can start from tens of meters!) and focusing at 1 meter. When focusing on a hyperfocal lens, as a rule, you have to point the lens at 1.5 -2 meters. It is very difficult to do this accurately using this scale.

Personally, I came up with a solution to this problem for myself. The same solution will help you aim a lens that does not have any focusing scale at all (a whale lens, for example) at the hyperfocal distance. I take a regular construction tape measure with me when shooting. And when I need to visit strictly at a certain distance, I lean it against the focal plane mark on the camera and extend the tape measure into the distance to the hyperfocal distance calculated before. After this, you can aim at the tip of the tape measure - it will be at the required distance. Of course, this method is very extravagant and I use it only in very difficult situations when the depth of field really needs to be used as accurately as possible. There is an easier way: knowing the hyperfocal distance, you can find an object in the frame located approximately at this distance and focus on it.

So, let's summarize

To accurately calculate depth of field, it is convenient to use depth of field calculators. You can install the calculator program on your smartphone and use it directly while shooting. Enter into the program various parameters of the shooting distance, lens focal length, aperture: see how the depth of field changes from this.

To achieve ideal sharpness, when calculating the depth of field, it is worth using a circle of dispersion with a diameter of not 0.03 mm, but smaller. It all depends on your requirements for sharpness in the photo and the technique used. When using insufficiently sharp optics, reducing the circle of dispersion during calculations will not provide any improvement. In my calculations I use a scattering circle diameter of 0.015 mm.

To distribute the depth of field in the image as accurately as possible, remember that it spreads unevenly from the focus point: some part of it goes forward from this point, and some (usually much larger) goes back.

To achieve sharpness from the objects closest to us to infinity when shooting a landscape, you should use focusing at the hyperfocal distance. The same depth of field calculator programs can calculate the exact distance at which you need to aim in order to obtain sharpness from ½ of this distance to infinity.

Remember that the sharpness and technical quality of a photo are often not as important as its artistic component. Be creative, experiment, look for interesting subjects, work on composition and lighting: this is what will make your photos interesting above all. And an accurate calculation of the depth of field will only help create a photograph at the proper technical level.

NIKON D810 / 18.0-35.0 mm f/3.5-4.5

DOF and hyperfocal distance are some of the basic concepts that a beginner photographer needs to learn. Let's figure it out in order - what it is and what it is used for in photography.

GRIP is an abbreviation for the words Depth of Sharp Space, she's the same Depth of field. In English, the abbreviation GRIP will be called Depth of Field or DOP. This is the region of space, or the distance between the near and far edges, where objects will be perceived as sharp.

Strictly speaking, ideal sharpness, from the point of view of physics, can only be in one plane. Where then does this area come from? The fact is that the human eye, despite all its perfection, is still not an ideal optical system. We don't notice the slight blurring to some extent. It is generally accepted that the human eye does not notice a point blur of up to 0.1 mm from a distance of 0.25 m. All depth of field calculations are based on this. In photography, this slight blurring of a point is called circle of blur. In most calculation methods, the diameter of the circle of confusion is taken to be 0.03 mm.

Based on the assumption that the human eye does not notice some blur, we will no longer have a plane of sharpness in space (called the focal plane), but a certain area that is limited by the acceptable blur of objects. This area will be called depth of field.

What does depth of field depend on?

The depth of field of the imaged space is influenced by only two parameters:

1. Lens focal length
2. Aperture size

How more focal length of the lens, the less depth of field. How wider the aperture is open (smaller f-number), the less depth of field. Simply put, in order to get the greatest possible depth of field, you need to use a wide-angle lens and close the aperture as much as possible, making its opening smaller. Conversely, to obtain a minimum depth of field, it is advisable to use a long lens and a wide open aperture.

In some sources, which are positioned as very authoritative, you can find the statement that the depth of field is also affected by the size of the matrix or film frame. Actually this is not true. The matrix size or crop factor itself does not have any effect on the depth of field. But why then is the depth of field in compact cameras with a small sensor size significantly greater than in SLR cameras with a large sensor size? Because as the matrix size decreases, the focal length of the lens required to obtain the same angle of view also decreases! And the shorter the focal length, the greater the depth of field.

Depth of field also depends on the distance to the subject - the closer you are to the lens, the shallower the depth of field, and the more pronounced the background blur.

How depth of field is used

Choosing the optimal depth of field depends on the shooting task. The most common mistake made by novice photographers who have recently purchased a fast lens is to shoot everything at the widest aperture. Sometimes it's good, sometimes it's not. For example, if you shoot a portrait with too shallow a depth of field, you may end up with the eyes in sharp focus but the tip of the nose not. Is it beautiful? The question is controversial. If a person's head is turned to the side, then the near eye may appear sharp, and the far eye may appear blurry. This is completely acceptable, but a client who does not know what depth of field is may have some questions.

Therefore, to obtain optimal depth of field when shooting portraits, you do not need to strive to always open the aperture. For most cases, it is better to cover it a couple of steps. Then the background will be pleasantly blurred, and the depth of field will be acceptable. When shooting group portraits, it is especially important to ensure such a depth of field so that all people are sharp. In this case, the aperture closes down further, to f/8 -f/11 when shooting outdoors and in good lighting.

Hyperfocal distance

What if we need, for example, to photograph a landscape where the foreground and background objects should be equally sharp? This is where the ability to use hyperfocal distance. This is the distance to the front edge of the field of view when the lens is focused at infinity. In other words, this is the same depth of field, but when focusing at infinity.

Depending on where it is more important to obtain maximum sharpness - in the foreground or on the most distant objects, they focus either at the hyperfocal distance or at infinity. In the first case, foreground details will be sharper, in the second - distant objects. Hyperfocal distance also depends on the focal length of the lens and aperture. The wider the aperture is closed and the shorter the focal length of the lens, the smaller the hyperfocal distance.

Both the foreground and background are sharp in this photo.

Calculation of depth of field and hyperfocal distance

To calculate the depth of field and hyperfocal distance, special tables are usually used. But I recommend using a more modern method, namely, a specialized program. It works online directly in the browser. The program is very easy to use and easy to figure out on your own. And the most important thing that will help you choose the right depth of field and hyperfocal distance is constant conscious practice!