We understand how different autofocus modes work for Nikon and Canon DSLRs. Achieve perfect focusing accuracy

Now in our photography course there will be a couple of rather boring, but necessary lessons on the way to professional photography. The first one is about working with focus. More specifically, how to properly adjust the focus, what are the focus modes, focus areas, and when is it better to use which focus mode.

Involuntary epigraph. I advise you to read this lesson of our photo school with digital, best of all with a mirror, camera in hand and try to apply what is written immediately in practice.

The games are over, and it's time to take the first step into adulthood. Today I will tell you in detail about focus and how to work with it. (I talked about what focus is and its basic properties in our Photography Lesson #3).

So. The camera needs to be shown WHAT to focus on. To do this, he has focus zones.

Focus zones.

The sizes of the focus areas can vary: from a simple point to a fairly large area.

This is what the focus area switch might look like.

With a dot, everything is more or less clear:

1. Choose where the focus will occur (for example, in the center of the frame or along the edges of the zone). In this case, focusing occurs only in the small square that you have selected.

2. Frame the frame. In this case, what you will focus on should be in the zone you have chosen.

3. Actually, take pictures.

In this case, you rigidly indicate where focusing will occur, taking away any initiative from the poor camera. In a camera, this type of focusing is called " single-zone autofocus.

In most cases, the focus area is left in the center. And in those rare moments when the focus object is not in the middle, they do this:

- put the object they want to focus on in the middle.

- press the shutter button halfway (in this position, the camera does not take a picture, but adjusts the focus. Shooting will occur if you press the shutter button all the way). They wait until the camera adjusts the focus, emitting, as a rule, a characteristic squeak (if it didn’t, read the “focus modes” below in the same chapter. You can throw the camera out if anything a little later).

- keeping the button pressed halfway, in order to keep the focus fixed, build the frame as necessary. For example, so that the subject is in the upper right corner.

- press the shutter button to the end. Get a professional photo.

In the second option, you choose a small area consisting of MULTIPLE points. And already move it in the viewfinder. It turns out that the focus is caught not by one point, but by a kind of trap for a point. This method is called "group dynamic autofocus"

The third way for the most courageous - you "give the camera" the entire autofocus area, and he already looks for the CLOSEST object in it and focuses on it. This method has a "simple" name. "autofocus with dynamic focus selection and closest subject priority".

That's all I wanted to tell you about focus areas. But this is not far from the end of the photo lesson. In order to completely confuse you, they also came up with focus modes. Although those villains who invented them sincerely believed that they were doing a good and useful deed.

Focus modes

When I talked about focus areas, I was answering the question "WHERE will focusing occur?". Now I will tell you how it will work.

Let's try to figure it out in order. There are three focus modes: tracking, single-frame and manual (who would have thought, but sometimes you need it too!).

This is what the focus mode switch might look like.

When should you use single-frame focus?

Single frame focusing is, in my personal opinion, the most perfect and easiest kind of focusing. It is usually the default on digital cameras. It works as follows.

First option. You press the shutter button halfway, not all the way. The camera focuses on the subject. Beeps and LOCKS focus. That is, it does not change it anymore. After that, you can (while holding the button halfway down) shift the frame in the direction you need and take a picture.

My friend, who often shoots with his favorite "soap box" in clubs, ran into a problem - in many club rooms it is too dark, and autofocus does not work there. He solves this problem in the following way. Looks for something in the illuminated area of ​​the club that is about the same distance as the object he wants to shoot. Focuses on a "light object",blocks autofocus, moves the camera to a dark place and already takes a picture.

The second option is even easier. Just select the subject and press the shutter button all the way down. The camera focuses and immediately takes the picture.

As I said, this method of focusing is most often used. It is the most accurate and is suitable for shooting still and slow-moving objects.

When should you use focus tracking?

Focus tracking is useful for shooting moving subjects. In fact, the camera is TRYING (keyword) to keep the moving subject in focus. That is, the focus motor works constantly and changes the focal length. But how he does it depends on where you shoot, and on what kind of object it is, and how fast it moves. And, of course, from the camera itself. This option can be useful when you're taking multiple photos in a row (or burst shooting).

The AF tracking mode starts working when you press the shutter button halfway. While you press it, the camera tries to keep the subject in focus. When you press the button, it will take a picture. If you let go, it will stop working.

When to use manual focus

How manual focus works is clear - with handles, my dear friend, with handles! Turn the focus ring or wheel, or pull the lever. And here are the cases when it should be used.

1. A small amount of light.

It is clear why. The camera itself does not see what to focus on - it is dark for it. Many cameras have an autofocus light that is designed to help with focusing, but it often fails.

2. Photo in motion.

Usually, in order to shoot moving objects, tracking autofocus is needed. But, if he does not cope and does not keep up with the object, then you can do the following. Use manual focus to set the camera to where the subject is expected to appear. When he appeared in this place, the main thing is to press the shutter button in time.

3. Shooting a portrait or some conceived complex composition.

When only some detail is in focus, it is often easier and more convenient to adjust the focus manually.

4. Shooting through glass or mesh.

Well, everything is clear here. The camera does not know that you need to shoot what is behind the fence, and stubbornly focuses on the reflection in the glass or on the grid. Therefore, it is necessary to forcibly adjust the focus on objects “behind the glass”.

5. Macro photography.

I will not explain what this is within the framework of this photo lesson. In a nutshell - shooting objects from a very close distance. So that in the frame they turn out very large.

The camera does not always willingly and obediently focus on such short distances. Sometimes they don't focus at all. Yes, and with focus areas is not so simple.

6. A photograph of the texture - a flat surface on which there are no contrasting places.

The fact is that autofocus is based on the contrast of colors. If you try to bring something that has a flat white surface to your eyes (for example, a sheet of paper), then you can easily notice that the eyes themselves begin to look for strokes, dashes, villi - anything. Because the eye cannot focus on a really monophonic material. Likewise for the camera. The greater the contrast, the easier it is to focus (especially in difficult lighting). And if the filmed is something monotonous and inexpressive, also poorly lit, then the camera may simply not focus on it, and you will have to use manual focus.

And finally. Each lens (or a camera with a lens, if they are indivisible "until death us do part") has a minimum distance at which it can focus. That is, closer - the image in the photo will already be blurry. You can find out this “critical” distance from the passport, from the scale on the lens ...

Or experimentally, having tried to shoot, gradually reducing the distance. By the way, it happens that the “passport” distance differs from the real one.

The maximum focusing distance is usually infinity. And it comes after a certain footage. I.e. Up to, for example, one and a half meters, you need to adjust the focus. After one and a half meters - no more. Anything further will be sharp.

I have given you a lot of information about focusing. All of it is applicable to most SLR cameras. The notation may be different, but the meaning remains the same. Cameras have different controls, the number of focus points, the availability of modes, but the principle remains the same. I would advise you to practice a little in different modes. Over time, you will, without hesitation, choose optimal mode. Well, when you become a professional photographer... Although you need it? Maybe it's better to just be a person who takes beautiful photos?

Publication date: 16.09.2015

Recently, we talked about how auto focus works in modern SLR cameras. But any type of focusing has several modes of operation. The photographer can choose from them the most suitable for a particular shooting situation. So what autofocus modes are there? When should one be used? Let's find out...

How to enable the desired auto focus mode on the camera?

Let's start simple: how do you switch focus modes on Nikon cameras?

• First, make sure auto focus is turned on at all. Check the switches on the lens and on the camera itself!

On the simplest models (for example, Nikon D3300 and Nikon D5500), it is important to follow only the switch on the lens. It should be in the AF position.

• Now that autofocus is enabled, select the desired mode.

• Ready! Now you can focus in the selected focus mode.

One-shot autofocus. AF-S

Single-frame autofocus, or AF-S (Auto Focus Single), can be called the main, basic autofocus mode. It is usually the default. In this mode, focusing occurs as follows:

Pressing the shutter button halfway activates the autofocus system;

The camera focuses on the point selected (by you or automatics), and then informs the user about this with a sound signal;

After that, the focus is locked at the specified position until the shutter button is pressed all the way (and the picture is taken) or simply released.

All the features of this regime follow from this simple algorithm.

• AF-S mode is good for shooting static scenes. Let's say you're shooting a landscape, still life, or a person posing for you. In this case, the focus object does not move anywhere. This means that you can focus on it once, and then calmly shoot or recompose the frame by holding the shutter button half-pressed. An important nuance: after the focus has been made and the camera has given a signal about this, you cannot change the distance between you and the object being shot (approach or move away from it). This will result in the subject being out of focus again. This is especially important when shooting portraits with high-aperture optics: there, changing the distance even by a couple of centimeters threatens that the model’s face will turn out to be blurry. If, however, the distance was violated, it remains only to focus again.

Nikon D810 / Nikon AF-S 50mm f/1.4G Nikkor

AF-S mode is great for staged portraits. The main thing is to remember that after focusing, you cannot change the distance between you and the subject, so as not to lose focus. After focusing, do not waste time in vain - shoot right away!

• AF-S mode is not suitable for shooting moving subjects. Since the focus is locked at a certain position after focusing, it cannot track fast moving objects in the frame. And there are quite a few of them in our world. These are frolicking children, and animals, and athletes, and all kinds of vehicles: bicycles, cars ... It is extremely difficult to shoot moving objects in frame-by-frame focus mode: there will be a lot of focus misses.

Nikon D810 / Nikon AF-S 18-35mm f/3.5-4.5G ED Nikkor

AF-S mode is great for landscape photography. It allows you to accurately select the desired focus point, after which the focus will not “run away” anywhere.

Continuous autofocus. AF-C

Focus tracking, or AF-C (Auto Focus Continuous), works differently. By half-pressing the shutter button, you turn on autofocus. It will now "follow" the subject at the selected focus point until a picture is taken or the shutter button is released.

Continuous autofocus is great for shooting fast-moving subjects. Use it for shooting sports, children's games, frolicking animals. There is a lot of diverse movement in the world - do not miss it! At the same time, modern 3D tracking technologies and dynamic focus point selection allow automation to select the appropriate autofocus point. A separate lesson will be devoted to how to work with zones and focus points.

Continuous autofocus is not suitable for shooting with recomposing the frame after focusing. A favorite trick of some photographers is to focus on the center focus point, and then, with focus locked, recompose the frame the way you like. This technique is inconvenient to use in continuous autofocus mode, because focus will be lost when recomposing the frame. The only option is to reframe the frame while holding down the AF-L button, which requires a fair amount of finger dexterity.

Nikon D600 / Nikon 80-200mm f/2.8 ED AF-S Zoom-Nikkor

It is more convenient to photograph animals of any degree of wildness with the AF-C focus mode. So they definitely won’t run out of focus at the time of shooting!

AF-A Mode

AF-A (Auto Focus Automatic) mode is available in amateur and advanced devices. (Nikon D750, Nikon D610, Nikon D7200, Nikon D5500, Nikon D3300). In this mode, the camera automatically determines which of the two autofocus modes (AF-S or AF-C) is appropriate in a given situation. AF-A mode is suitable for beginner photographers: it allows you not to think about choosing an autofocus mode, the camera will make the choice for you.

Autofocus Modes for Live View Shooting

From a recent article on autofocus types, we know that focusing through the viewfinder and through the Live View screen involve completely different mechanisms. Focusing through the camera screen uses a type of autofocus called contrast focus. It has its own modes of operation.

One-Shot AF-S

This mode is similar to the mode of the same name, available when focusing through the camera's viewfinder. When half-pressing the shutter button, the camera focuses on the selected point. Once the operation is successful, focus is locked until a picture is taken or the shutter button is released.

And here continuous autofocus AF-F works a little differently than AF-C. Focusing is performed not when the shutter button is half-pressed, but when it is released. That is, constantly. When the shutter button is pressed halfway, focus is locked. This method allows you to constantly monitor the subject, not losing sight of it for a second.

AF lock with AE-L/AF-L button

We know that autofocus is locked in AF-S single focus mode after focusing by holding the shutter button halfway down. But in AF-C mode, this does not happen, and autofocus “follows” the object to the bitter end. However, in both modes, the focus can be locked at the position it is currently in. To do this, there is a button to lock autofocus and auto exposure AE-L / AF-L (Auto Exposure Lock / Auto Focus Lock). Thus, by pressing this button, you will lock both the focus and the exposure parameters in the position in which they are. However, in the camera settings, you can independently specify what to block with this button - both parameters, only exposure or only focus.

Focus modes

The focus mode that everyone usually works in is One Shot AF. It suits any static scene, and sometimes slow moving objects. When you shoot in One Shot AF, you compose the scene using the viewfinder and press the shutter button halfway. The autofocus system turns on and the lens focuses directly on the main subject. At this stage, a green light will light up to confirm focus, and you can also hear an audible confirmation.

Once the camera has set a focus point, it locks it. If you don't release your finger from the shutter button, the focus will not change - even if you move the camera. This useful feature is called "Focus Lock". It allows you to first focus on some point outside the scene, and then turn the camera around and compose. For example, imagine you are photographing a landscape. The camera may want to focus on the furthest hills, and you want to increase the depth of field by focusing on a point that is closer to the camera. All you have to do is tilt the camera down a bit to bring this dot into view. Now press the shutter button halfway, make sure the camera has focused (the green confirmation light will turn on), and keep the shutter button half pressed while composing your scenery.

The One Shot AF mode has another useful feature. The camera will not let you shoot if the lens is out of focus. If the focus confirmation signal flashes, it means that the lens failed to focus and after pressing the shutter button completely, nothing will happen.

Shutter button

The shutter button on your EOS camera is actually a two-position electrical switch. Partially pressing the button activates the first switch (Canon calls it SW-1). After the first press, the autofocus and metering systems turn on. In low light conditions (depending on the selected shooting mode), the built-in flash may pop up. To help the camera focus in low-light conditions, the AF-assist beam may light. Pressing the shutter button fully activates the second switch (SW-2) and starts the following chain of actions:

• the mirror inside the chamber is lifted up to allow the light to reach the rear of the chamber
• the shutter mechanism starts - the shutters open and the film (or digital sensor) begins to receive a light flux
• if the built-in flash is raised or an external Speedlite is attached to the camera and turned on, the flash fires
• the mirror returns to its original position
• the shutter returns to its original position and is ready for the next exposure

AI Servo AF Mode

AI Servo AF is essentially One Shot AF, but without focus lock. The lens automatically refocuses every time the distance between the camera and the subject changes. This feature is very useful when photographing moving subjects. This mode is most often used in sports photography. However, they must be used with caution. In this mode, you can take a picture even when the lens has not yet focused or failed to focus. In addition, if a moving object appears between the camera and the subject, the lens may focus on an object that is closer to the camera. All this can lead to out-of-focus images.

In AI Servo AF mode, the green focus confirmation light will not light up, and you will not hear a confirmation beep (even if it is turned on). However, in both One Shot AF and AI Servo AF, the green light will blink if the camera is unable to focus on the subject.

There is a slight delay between lens focusing and shutter release. Although it is measured in fractions of a second, it can be taken into account when shooting fast moving objects - for example, a racing car at a speed of 160 km/h travels about 4.5 m in 1/10s. This means that while the machine may have been in focus when the shutter button was pressed, it may not be in focus when the shutter itself opens.

Many EOS cameras solve this problem with predictive focus technology. The camera measures the distance to the subject every time the lens is refocused. By analyzing this data, the camera can calculate the speed and direction of the object. It then extrapolates this information to determine where the subject will be when the shutter is released. The camera then refocuses the lens to the calculated distance so that the subject is in focus at the moment of exposure. The predictive focus mode is activated automatically when it is needed.

Custom function

In One Shot AF mode, half-pressing the shutter button activates the autofocus system. Once the camera has focused, it will maintain that focus as long as you keep pressing the shutter button. This means that you can focus on an arbitrary point, and then you can turn the camera and compose the scene without changing the focus.

Focus lock is effective when the main subject is not well lit or has insufficient contrast for the lens to focus on. In this case, you focus on any other subject at the same distance from the camera as the main subject.

Focus lock mode is not available in AI Servo AF - the lens will constantly refocus as you move the camera. However, setting CF 4-2 on the EOS 1N and 1V cameras allows AI Servo AF to be paused by pressing the AE Lock button.

AI Focus Mode

The third focus mode - AI Focus - is actually a combination of the first two. Most of the time the camera is in One Shot AF, but if the focus sensor detects that the main subject is moving, the camera will automatically switch to AI Servo AF and start tracking the subject.

How does the camera determine that the subject is moving? As soon as we half-press the shutter button, the focus sensor starts to work constantly. If the focus distance changes, the camera determines that the subject is moving - and can determine the speed of movement. As soon as this speed exceeds a certain threshold, the camera switches to AI Servo AF mode.

Typically, AI Focus mode is used on inexpensive EOS models - it is supposed to be used by people with little experience in photography. With AI Focus, we can focus on the scene and let the camera choose the best shooting mode for you.

On some models, different autofocus modes are set by the camera based on the selected shooting mode - for example, One Shot for landscape mode and AI Servo for sports mode.

All lenses in the EF range support autofocus. However, there are some non-EF lenses in the EOS system that need to be manually focused. These are the Tilt&Shift lenses - TS-E 24mm/45mm/90mm, as well as the MP-E65 f/2.8 1-5x Macro lens.

Autofocus modes

Camera	One Shot AF	AI Servo AF	AI Focus	Manual
EOS 1
EOS 1N
EOS 1N RS		(·)
EOS 1V
EOS 10
EOS 100
EOS 1000/F/N/FN
EOS 3
EOS 30/33
EOS 300
EOS 300V
EOS 3000
EOS 3000N
EOS 5
EOS 50/50E
EOS 500
EOS 500N
EOS 5000
EOS 600
EOS 620
EOS 650
EOS 700
EOS 750
EOS 850
EOSRT		(·)
EOS IX
EOS IX 7
EOS 1D
EOS 1Ds
EOS 10D
EOS D2000
EOS D30
EOS D60
EOS DCS3

This table shows the autofocus modes of EOS cameras. You can set the mode yourself [·], or the camera itself sets the autofocus mode depending on the selected shooting mode [o]. All cameras except the EOS 650 and 620 have a predictive focusing system with AI Servo AF.

(·) - AI Servo AF mode is not available when the EOS 1N RS is set to RS mode (similarly when EOS RT is set to RT mode).

Selecting the AF Mode

It's always good to know what the camera does - in this table you will find all the necessary information.

Selecting the AF mode is possible only in the Creative Zone (P, Tv, Av, M, DEP), and only on some cameras. In other shooting modes, the camera itself makes a choice:

Camera						Machine	Portrait	Scenery	Macro	Sport	Night
EOS 1
EOS 1N
EOS 1V
EOS 10
EOS 100
EOS 1000/F/N/FN
EOS 3
EOS 30/33
EOS 300
EOS 300V
EOS 3000
EOS 3000N
EOS 5
EOS 50/50E
EOS 500
EOS 500N
EOS 5000
EOS 600
EOS 620/650
EOS 700
EOS 750/850
EOSRT
EOS IX
EOS IX 7
EOS 1D
EOS 1Ds
EOS 10D
EOS D2000
EOS D30
EOS D60
EOS DCS3

U - the user chooses the mode himself
OS - One Shot AF Mode
AF - AI Focus AF Mode
AS - AI Servo AF Mode

Manual focus

And finally, there is a manual focus mode. It can be used with any EOS camera, but the function is not a camera, but a lens. Look at the side of the lens, next to the red dot - you will see a switch with two positions - "AF" and "M". Switch it to the "M" position and the lens will no longer focus automatically. Instead, it will focus according to how you turn the focus ring on the lens itself. The only non-manual EF lens, the EF 35-80mm f/4-5.6 PZ, was a Power Zoom lens sold with the EOS 700.

All EF lenses have been designed with auto focus in mind. If you have used older FD lenses, the manual focusing of EF lenses may not seem as smooth to you as on fully manual FD lenses. Also, from infinity to the closest distance, the focusing ring scrolls rather quickly, making precise focusing difficult in some cases. Be that as it may, it depends on the particular lens.

In general - why do you need manual focus on autofocus lenses? There are some situations where the autofocus system will find it quite difficult to handle: scenes with low contrast - for example, landscapes in fog or the expanse of the sea; scenes with low illumination (in fact, this is a special case of a scene with low contrast); extremely bright reflections from water, ice or metal; objects that move too fast to be automatically focused; scenes in which the main subject is not closest to the camera (for example, an animal in a cage behind bars).

If the main subject is close to the camera, the focus assist system built into the camera (or the more powerful one in the Speedlite) can help, but it only works if the subject is not very far away.

In all such situations, the best way out is to manually focus the lens.

Many USM lenses allow you to manually focus immediately after autofocusing - without the need to constantly switch between manual and auto focus modes. This feature is called Full-Time Manual Focusing (FTMF). This is particularly useful when using telephoto lenses to make final adjustments to focus just before shooting. You can check if your lens has this feature by turning the ring right after autofocusing ends.

How to choose autofocus mode?

The AF mode is only selectable in the Creative Zone (P,Tv,Av,DEP,M). In fully automatic mode (green square) and PIC modes, the camera itself sets the autofocus mode (see table). You just have to make sure that the lens is properly mounted on the camera and is in autofocus ("AF") mode.

EOS 1, 600, 620 and 650 cameras display "M.Focus" when the lens is switched to manual focus mode; on other models, switching to manual mode is not displayed.

After autofocusing, you can lock the focusing distance by setting the lens to "M" mode. This will allow you to remove your finger from the shutter button, compose, and take the picture at the original focus distance.

EOS 1, 1N, 1V, 1D, 1Ds, D2000, DCS 3
Press the AF button on the top left of the camera and turn the parameter dial at the same time until "One Shot" or "AI Servo" is displayed in the upper right corner of the LCD.

EOS 10
Press the yellow AF button on the back of the camera and turn the parameter dial at the same time until "One Shot" or "AI Servo" is displayed in the upper right corner of the LCD.

EOS D30, D60
Press the AF button on the top right of the camera and turn the parameter dial at the same time until "One Shot" or "AI Servo" is displayed in the upper right corner of the LCD.

EOS 10D
Press the AF button on the top right of the camera and turn the parameter dial at the same time until "One Shot" or "AI Servo" is displayed in the lower right corner of the LCD.

EOS 1000/F, 1000/FN, 300, 300V, 3000, 3000N, 500N, 5000, 700, 750, 850, IX7
The autofocus mode is set automatically by the camera depending on the shooting mode.

EOS 30, 33, 50, 50E
Switch the AF mode dial to "One Shot", "AI Focus", or "AI Servo".

EOS 5
Press the AF mode select button on the back of the camera. Turn the parameter dial until the LCD displays "One Shot", "AI Focus" or "AI Servo". If you release the AF mode select button, the selected mode will be active for 6 seconds.

EOS 600, 620, 650, RT, IX
Press the AF mode select button located under the flap on the back of the camera. Turn the dial until the LCD displays "One Shot", "AI Focus", or "AI Servo" (on the EOS 620 and 650 it's just "Servo").

Photos - David Hay, Paul Exton

a source eos.nmi.ru 2002-2006 Alexander Zhavoronkov

Article text updated: 12/13/2018

Many modern SLR cameras are equipped with such advanced autofocus systems that it is often difficult to figure out how to use them. It doesn't matter if we're shooting with an entry-level camera or a professional camera, in order to get sharp pictures, we need to try to figure out how to use the different autofocus modes. Incorrect focusing, a blurred image can destroy the positive impression of the picture, and it is impossible to correct this shortcoming during post-processing in a graphics editor. Some photographers convert their photos to black and white to hide focus issues. If we learn how to focus correctly, we don't have to resort to these kinds of tricks, we get a much better result that our viewers will love. A clear image is what people want to see today when looking at our pictures. Someone may argue that sometimes a fuzzy picture looks “creative”, but here you need to understand: it’s one thing when we smear a photo for a specific purpose, and another when we spoil the picture because we don’t understand the work of our camera’s focusing system. Once we understand how DSLR autofocus works, we can decide for ourselves when and to what extent the image will be out of focus.

Photo 1. Lessons for beginners. To get a high-quality photo, you need not only to choose the correct shutter speed, autofocus mode, but also be able to quickly rotate the zoom ... Nikon D610 camera. Nikkor 70-300 telephoto lens. Settings: ISO 1000, FR-98mm, f/5.0, V=1/2500 second

In today's free photography tutorial, we'll cover the basics of autofocus modes on DSLRs. Since the operation of automatic focus directly depends on what type of camera and its model we use, we, of course, will not describe in detail absolutely all AF modes, but will analyze a couple or two examples for clarity. Since I myself now have a full-frame Nikon D610 camera, and before there was a cropped Nikon D5100 camera, more emphasis will be placed on the work of this manufacturer's DSLRs. Well, I beg your pardon for absolutely beginner amateur photographers for the fact that the photo lesson will use specific vocabulary that is more understandable for advanced photographers.

1. How the autofocus system of SLR cameras works

One of the nice things about modern cameras compared to their film counterparts fifteen years ago is that we no longer have to manually adjust the focus. Digital photography is much more friendly to the amateur photographer in this aspect, because, unlike film photography, we immediately see the result and can easily change settings, retake a photo without thinking about the cost of film and photo paper. Over the past ten years, autofocus systems have improved significantly, and even entry-level DSLRs boast a good autofocus complex. Well, how does such a system work in modern SLR cameras? Let's start with the very basics.

1.1 Active vs passive autofocus

There are two types of autofocus (AF) system: active and passive. Active AF “Active AF” functions by sending an infrared beam at our subject and picking up its reflection (“sounder” principle). The camera makes calculations and understands how far the object is from it, signals to the lens how much to adjust the focus. A nice advantage of the active focusing system is that it can work in very low light conditions, in which normal (passive) autofocus will fail. The disadvantage of “Active AF” is that this mode can only be used in stationary conditions, for shooting motionless subjects, and works only at short distances: up to 5-6 meters. If we take pictures with a Nikon or Canon flash that has an AF Assist function, it will work in active auto focus mode.

The “Passive AF” autofocus system is based on a completely different principle: it does not send an IR beam and does not pick up its reflection in order to understand how far between the camera and the focus object. Instead, special sensors inside the chamber are used to contrast definitions part of the light passing through the lens (called the “phase method”), or the camera matrix itself serves as such a sensor that determines the contrast of the image (called the “contrast method”).

What is meant by "defining contrast"? Without going into the wilds of terminology, this is the definition of sharpness in a certain area of ​​\u200b\u200bthe image. If it is not sharp, then the autofocus system adjusts the lens until sharpness / contrast is achieved.

This is why the passive autofocus system needs enough contrast in the frame to function properly. When the lens starts to “scrawl” over a uniform surface (such as a white wall or some kind of smooth tonal surfaces), this is because the camera needs objects with edges (contrast) that separate from the background in order to understand how adjust focus.

By the way, if there is an AF assist lamp on the front panel of our DSLR, this does not mean that the camera is in active focus mode: all that the lamp does is illuminate our object like a flashlight, i.e. The camera is operating in “passive AF”.

Many digital cameras, such as point-and-shoot cameras, camcorders, and the like, most often use a "contrast AF method" to achieve focus. At the same time, most modern DSLRs can be equipped with both systems for focus correction: phase and contrast autofocus.

Since the “contrast method” requires light to hit the sensor, the SLR camera must have the mirror up when focus is determined, which means that contrast autofocus in a DSLR can only be performed in “Live View” mode.

The phase method is great for focusing on moving objects, and the contrast method is great for stationary ones. Contrast-detect autofocus often performs better than phase-detection AF, especially in low light conditions. The advantage of contrast focusing is that it is enough to use any part of the image (including the one at the very edge) on the matrix to adjust the sharpness, while phase focusing requires the use of one or more focus points of the SLR. The disadvantage of the contrast method today is that it is relatively slow.

Many professionals believe that camera manufacturers will be able to solve this problem in the foreseeable future, as the speed of autofocus when shooting video is becoming more and more important for DSLRs, and some mirrorless cameras (in particular, the Micro Four Thirds, 4/3 standard) are already equipped with fast contrast AF. Modern high-end mirrorless cameras have two autofocus systems: a fast phase-detection autofocus for working in good light and a slow contrast autofocus for low-light conditions. Some manufacturers, in general, managed to embed the pixels of phase sensors directly into the camera matrix, which, in comparison with the traditional phase autofocus system of DSLRs, greatly increased the accuracy of the system.

If all of the above sounds confusing, don't get too upset: the technical information provided above is intended to provide a general understanding of how autofocus works in a camera. Just remember that focus errors in the camera happen due to the lack of light passing through the lens and the type of focus mode we have chosen (as explained below).

1.2 Focus points

Focus points are small empty rectangles or circles that we can find in our camera's viewfinder. Manufacturers often differentiate between amateur and professional cameras by building different autofocus systems into them. Entry-level DSLRs typically have a minimum number of focus points to focus on, while advanced DSLRs come with a complex, highly configurable AF system with a large number of focus points. They are part of the "Phase AF Method" so that each point can be used by the camera's AF sensor to determine contrast.

Focus points are deliberately located in a certain part of the frame, and their number differs not only from different manufacturers, but also from different models of cameras. Here is an example of two different types of autofocus with a different number of focus points and their arrangement.

As you can see, the Nikon D5100 DSLR has 11 points, while the Nikon D810 has 51 of them - a big difference in the number of sensors. Does the number of focus points matter? Certainly - yes! This is not only because it is easier for us to compose a particular shot by focusing on a specific area of ​​the image, but also because the AF system can more effectively track the subject in the frame (extraordinarily handy when shooting sports and wildlife). Although, it must be borne in mind that not only the number of focus points in our camera matters, but also their type.

1.3 Types of points in the DSLR AF system

Let's talk about the different types of autofocus points in DSLRs. As stated above, the number of points is not the only important parameter of an autofocus system. The type of points is also critical to achieving accuracy. There are three types of focus points: vertical, horizontal And cross. Vertical and horizontal work in the same direction, i.e. these are linear sensors. Cross dots measure contrast in two directions, making them more accurate. Therefore, the more cross sensors in our DSLR, the more accurate the AF system works.

That's why, when a new model of a SLR camera is announced, in the review we can read something like: "The number of focus points is X, of which Y is a cross type." The manufacturer proudly emphasizes the number of points, especially the presence of cross points, if there are more of them in a new camera. Here, for example, in the list of the main differences between the Nikon D7200 and Nikon D7100 from the earlier model Nikon D7000, it was indicated that they have 51 focus points, including 15 cross points, and the old woman has 39 points, cross points - 9 pieces.

When we buy a new SLR camera that we plan to use for shooting sports or for hunting, we need to pay close attention to both of these parameters.

1.4 Other factors affecting the efficiency of the camera's autofocus system

As we can see, both the number of focus points and their type are important. Although, not only they affect the operation of auto focus. The quality and quantity of light is another parameter that greatly determines the performance of autofocus. Every photographer has probably noticed that the camera focuses perfectly when shooting on a bright sunny day on the street, and as soon as we enter a dimly lit room, the lens starts to “scour”. Why it happens? Because, in low-light conditions on the subject, it is much more difficult for the camera to measure the differences in the contrast of the scene. Remember that passive autofocus is completely dependent on the light passing through the lens, and if the quality of the lighting is poor, then autofocus does not work satisfactorily.

Speaking about the quality of light, we should not forget about the features of the lens, that the maximum open aperture also has an effect on AF. If we shoot with old glass that has mold, dirt, too much dust, or there are problems with front and back focus, then auto focus, of course, will not work very accurately.

This is why professional lenses at f/2.8 allow you to focus much faster than amateur lenses at f/5.6. The f/2.8 aperture is the most suitable for fast focusing: the aperture is not too wide, not too narrow. By the way, usually lenses at aperture 1.4 focus more slowly than at f / 2.8, since more rotation of the glass elements inside the structure is required to correctly focus .

Focusing accuracy is important at these wide apertures because the depth of field is very small. Ideally, the aperture should be between f/2.0 and f/2.8 for the autofocus system to function at its best.

Smaller apertures, such as f/5.6, will cause less light to pass through the lens and make it harder for the autofocus system to work. For this reason, open apertures (with the exception of f/1.4) are preferable to clamped ones.

It should also be added that all modern digital cameras focus at an open aperture, so no matter what aperture value we choose (for example, f / 22), the aperture changes only at the moment of shooting .

Finally, the overall quality and safety margin of the autofocus system is of the highest importance. For example, the top professional Canon 1D Mark III DSLR, designed for shooting sports and hunting, after being released into the series, spoiled its reputation due to problems with autofocus. And it took forever for Kenon to release firmware to fix these shortcomings that annoyed professional photographers. Many of them switched to Nikon cameras precisely because of focusing problems. The camera was equipped with all autofocus modes, but it did not work correctly under certain conditions.

If we want the best autofocus system in today's DSLRs, especially for sports and wildlife photography, Nikon or Canon should be the choice (although other manufacturers are quickly catching up with the market leaders).

2. Autofocus modes of digital DSLRs

Most DSLRs these days have the ability to shoot in a variety of out-of-focus modes depending on the situation.

It is one thing when we photograph a portrait of a calmly sitting person, and another when we shoot a running athlete or a flying hawk. When we shoot a stationary object, we focus once and take a photo. But in case the subject is in continuous motion, we need the camera to automatically adjust the focus at the moment when we take the picture. The good news is that our camera has a built-in function to work effectively in this situation. Let's look at each of the focus modes in more detail.

2.1 One-Shot Focus Mode

Single-frame tracking focusing in Nikon cameras is designated “AF-S”, in Canon cameras this type is called “One-shot AF”. And it is an easy way to bring the lens into focus directly. We choose a focus point, and the camera measures the contrast simply by one point.

If we press the shutter button or the assigned AF button (if this assignment is possible in our model) halfway, the camera focuses, but if the subject moves, it does not refocus, even if we continue to keep the shutter button pressed halfway. That is, the focus remains "locked".

Normally, in single-servo AF mode, the camera must first focus in order for the shutter to be released. Therefore, if focus fails or the subject moves, pressing the shutter button will do nothing (due to a focus error). In some camera models it is possible to change the camera's reaction to the lack of focus (for example, with the Nikon D810 we can set the “AF-S Priority Selection” setting in the “Shutter” custom settings menu, which will allow us to take a picture even if the camera is not in focus) .

There are a few things to keep in mind about AF-S mode: if we have installed an external flash that has a red AF-assist beam, it will require the camera to be set to AF-S mode for it to work. The same is true for the autofocus assist lamp built into the front panel of the camera: it only works in AF-S mode.

2.2 AI Servo Focus Mode

Another focusing method available in modern DSLRs is called "Continuous Servo AF" or AF-C by Nikon and "AI Servo AF" by Canon. It is used to track moving subjects, and is essential when photographing sports, wildlife, and other non-stationary subjects. The principle of operation of this mode is based on analyzing the movements of objects and predicting where it will be in the next instant, and setting the focus to this point.

The advantage of this mode is that the focus is automatically re-adjusted if the photographer or subject moves. All that is needed is to continue to hold the shutter button (or the assigned AF key, if possible) in the half-pressed state. The autofocus system will automatically track the subject. Compared to AF-S single-servo focusing, AF-C continuous focusing is typically highly customizable (especially on the most expensive DSLRs) and can perform complex tasks such as tracking subjects to one or more focus points.

2.3 Hybrid One-Shot and Tracking Focus

Some cameras also have another mode called "Auto Servo AF" "AF-A" for Nikon or "AI Focus AF" for Canon cameras. It is a kind of hybrid, automatically switching between single-frame and continuous focusing. If the camera determines that the subject is still, it switches to AF-S, and if the subject is moving, it switches to AF-C.

In cheap DSLRs, AF-A mode is enabled by default and works decently enough in many situations. Many professional cameras do not have Auto Servo AF as it was designed for beginners.

2.4 Continuous focus tracking

Continuous focus focus mode, designated by Nikon with the letters “AF-F”, was introduced by the company for the new Nikon D3100 and D7000 models. It is intended mainly for shooting in Live View format. In this mode, the camera follows the subject and automatically adjusts the focus during video recording. Although the name sounds nice, in real life this mode does not work very well when shooting fast moving objects. Nikon Corporation engineers still have a lot of work to do to bring the “AF-F” mode to perfection. If you do not shoot video on a DSLR, then you should not turn on this mode.

Many professional photographers in photography lessons for beginners note that most of the time they have AF-C continuous focus tracking turned on, and only when the camera cannot focus in poor lighting conditions, they switch to AF-S.

2.5 Changing focus modes

If you do not know how to change the auto focus mode on your camera, it is better to read the instructions for it, as this happens differently for different models. For example, for entry-level cameras Nikon D5300 or Nikon D5200, you need to press the "Info" button and select the focus mode with the joystick. And expensive DSLRs have a special button on the front panel, with which you can quickly switch between different modes. Here, for example, is how to change the AF mode on the Nikon D610 camera: press the AF mode button and simultaneously turn the control wheel.

The letter “C” appeared on the auxiliary screen, which means the camera is working in AF-C continuous focusing mode, switched to “S” - frame-by-frame focus turned on. Press "M" - switched to manual control of the camera focus.

3. AF area modes

To confuse novice photographers even more, many SLR cameras have items in their menus called something like “AF area mode” that allow the amateur photographer to select several options for how focusing will work in AF-S, AF-C, AF- A and AF-F.

For entry-level DSLRs, such as Nikon D3100 or Nikon D5200, the settings can be changed through the menu, while for advanced cameras, such as Nikon D300s, Nikon D700, Nikon D3s or Nikon D3x, they are changed with a special selector on the rear panel (for SLR cameras, Nikon D810 and Nikon D4S cannot be reassigned to control this parameter to other buttons). Let's see what the AF area selection gives us.

3.1 Single point focusing area

When we select "Single Point AF" on a Nikon camera or "Manual AF Point" on a Canon camera, we only use one point to focus through the viewfinder to focus. That is, when we switch from one point to another with the joystick, the camera measures the contrast only in this particular section of the image, using vertical or cross sensors (depending on which one we have chosen). Many professional photographers advise using the single-point focus mode when shooting landscapes, architecture, and other stationary subjects.

3.2 Dynamic Focus Area Mode

In "Dynamic AF" mode for Nikon or "AF Point Expansion" for Canon cameras, we select one focus point, and the camera first adjusts focus on it. Further, once the focus is set, if the subject is moving, the camera will use the surrounding points to follow it and keep the focus on the subject. We expect it to follow the movement of the subject and keep it in focus while keeping the camera close to the initially selected focus point. If the camera selects surrounding/other points, it will not be visible in the viewfinder, but it will be noticeable in the finished photo.

Dynamic AF works great when shooting fast-moving subjects such as birds, because it's not easy for us to keep a bird in focus while it's flying. Advanced DSLRs, such as Nikon D7100, Nikon D7200 or Nikon D800, allow you to choose the number of dots surrounding the main one: 9, 21 or 51 pieces.

Thus, when we want to track a small area in the frame, we select 9 points, and if we need to track movement across the entire field of the frame, we assign 51 points.

Recently, many Nikon DSLR models also have a “3D tracking” mode - when we assign a point, and the camera then decides how many auxiliary ones it needs to track the change in the position of the object in the frame. The advantage of the 3D tracking mode is that the camera uses a built-in image recognition system, automatically reading colors and following the subject on its own, and you simply compose the picture while the subject is moving.

For example, we photograph a white heron pacing among black birds. System 3 Dtracking will automatically focus on a white bird and follow it even if the bird moves or the camera moves, allowing us to compose the shot .

If we compare the modes "Dynamic AF" and "3D Tracking", then in the first case a certain number of points will be used, and in the second - all available to follow the subject. In this case, "Dynamic AF" uses certain "zones", activating only the surrounding focus points (as many as we have selected in the settings). For example, we have selected 9 points, tracking will work as long as the object is in the zone of 9 focus points surrounding the main one. If the subject leaves this area, the camera will not be able to focus. But in the 3D tracking mode, the camera will continue to observe the object (the newly selected points will be displayed in the viewfinder), even if it is significantly farther away from the originally selected point.

Professionals use the dynamic autofocus mode during bird and wildlife photography, using a small number of points: 9 or 21 pieces. There are different opinions about 3D tracking, as it is not as fast as with, for example, 9 dynamic AF points.

3.3 Auto focus area selection mode

For Nikon cameras, it is referred to as "Automatic AF area selection", for Canon - "Automatic AF Point Selection" and is a point and shoot method of focusing. The camera automatically chooses what to focus on. This is a complex system that can recognize the color of a person's skin in the frame and automatically focus on it. If there are several people in the frame, the focus will be selected on the one closest to the camera. If there are no people in the frame, then, usually, the camera focuses on a near or far object. If we have selected AF-S and Auto-area AF modes, the viewfinder will display the engaged focus point for a second, allowing us to confirm the area the camera has focused on.

The same is possible with Canon cameras, but they have this mode called “Automatic AF point selection in One-Shot AF mode”. It's hard to say why this mode is needed, because professionals like to control all the shooting parameters, instead of letting the camera do it for them.

3.4 Group focus area mode

The latest Nikon SLR cameras, such as the Nikon D810 and Nikon D4S, have a new focus area selection mode “Group AF”. Unlike "Single-point AF", not one, but five focus points are used to track subjects. This mode is better for setting the starting point for focusing and tracking subjects than "Single-point AF" or "Dynamic AF", especially when it comes to shooting small birds that constantly flutter from branch to branch and can be difficult to catch in focus and follow them. In such cases, “Group AF” can be of great help to the photographer and produce better results than “Dynamic AF” because it is more accurate and gives shot-to-shot stability.

How does the group focus area mode work? We see 4 focus points in the viewfinder, the fifth, in the center, is hidden. We can move the group by pressing the joystick on the back of the camera (ideally we want to stay in the center because the focus point in the middle of the frame is a cross point, more accurate). When we have aimed at the subject, all five points are activated at the same time for initial focusing with priority on the nearest subject.

This is different from "Dynamic AF" with 9 points, which has priority on the selected center point. If it was not possible to focus on the central one (low contrast), the camera will try the remaining 8 pieces. Initially, the camera always focuses on the center point, and only then moves on to the other 8 pieces.

In turn, “Group AF” uses all 5 points at the same time and tries to focus on the nearest subject without giving the advantages of any of the 5 points.

Group AF mode “Group AF” is especially useful for shooting birds, wildlife, and non-team sports. In the cyclist example above, if our goal is to focus on the athlete in front, Group AF would be a better choice, as this mode will keep the camera following the athlete closest to it.

Another good example is a bird sitting slightly above the photographer so that the background behind it is almost invisible. In Dynamic AF mode, no matter where you aim, the camera will first try to focus. If we aim the lens directly at the bird, the camera will focus on it. If we accidentally aim at the background, the camera will focus on it.

Therefore, shooting small birds can be a little difficult, especially in bushes, or if the branches on which they sit are constantly staggering. The choice of the initial focus point is very important, and the sooner we choose it, the higher the chances of catching the bird in focus and following it, especially if it suddenly decides to fly away. As stated above, the “Group AF” mode does not benefit from any focus point, all 5 pieces are activated at the same time. In this case, since the bird is sitting closer than the background, once the group of 5 points is close to it, the camera will always focus on the bird and not the background. Once we have selected focus, the camera in Group AF will follow the subject, but again only if one of the 5 points is next to the subject. If the subject is moving fast and we don't have time to turn the camera in the same direction, the focus will be lost, just as it would be with 9-point Dynamic AF.

Some photographers say that the "Group AF" mode allows you to capture focus quite quickly, but no one really measured whether it is faster than 9-point dynamic focusing. Perhaps the latter in some situations will be faster.

Another important fact to pay attention to is that when we turn on the group auto focus mode when focusing single frame AF— S, the camera turns on the face detection function and tries to focus on the eyes of the person closest to it who stands out from the group. For example, if we are photographing someone standing between the branches of a tree and foliage, the camera will always try to focus on the subject's face, instead of focusing on the leaves. .

Unfortunately, face detection is only possible in AF-S mode, so if we are photographing a group of fast moving athletes and we need the camera to lock focus and follow the faces of the subjects (rather than focusing on nearby objects), we are better off using the Dynamic mode. AF" for Nikon or "AF Point Expansion" for Canon cameras.

Here is a schematic comparison of each of the auto focus modes for Nikon cameras.

When viewing images clockwise: Single-point AF, Auto-area AF (9, 21, and 51), 3D Tracking, and Group AF.

3.5 Other focus area selection modes

Latest DSLRs have new area selection modes such as Face Priority AF, Wide Area AF, Normal Area AF, and Subject Tracking AF. These modes are used when shooting video on a SLR camera. Most likely, these functions will be built into the entire line of Nikon DSLRs capable of shooting video. We will not discuss these modes in detail, since their functioning in different cameras is slightly different and may be changed in the future.

Canon also has its own AF area selection modes such as “Spot AF” where we can fine-tune focus within the focus point. This mode is highly specialized, it can be found, for example, in Canon EOS 7D cameras.

3.6 When to choose one or another type of auto focus

Why do we need to know how and when to use the different AF area selection modes? Because each of them can be combined with the focus mode! To better understand this, let's make a table with examples (for Nikon SLR cameras).

AF area selection mode	Nikon focus modes
Single point AF	The camera focuses only once and only on the selected focus point.	The camera focuses on one selected point, when the object moves, the focus is reconfigured.	The DSLR detects whether the subject is moving or stationary and automatically decides which mode to use: AF-S or AF-C. In either case, only one point applies.
Dynamic AF	Disabled, just works like single point auto focus.	We choose an initial focus point, and once the camera is on the subject, the surrounding points are turned on to track its movement. You can select the number of auxiliary points in the camera menu.	As in the previous case, but by a group of points.
	As in the previous case	Instead of using a specific number of focus points, all possible ones are used and color recognition is used to track the subject. The photographer specifies the starting point, and the camera follows the subject across the frame automatically, allowing him to recompose the shot without losing focus on the subject.	Similar to the previous
	The camera activates 5 focus points and aims at the nearest subject. If he determined that there is a person in the frame, he will focus on him.	The camera automatically focuses on the nearest subject and tracks it into the frame as long as it is close to 5 points. Face recognition doesn't work.	Not available.
Auto-area AF	The camera itself chooses a point depending on what is in the frame.	The camera itself sets a point on a moving object and follows it.	Similar to previous cases.

Note to the table of explanations of the focus area selection modes above: certain options may not be available in different models.

3.7 Changing focus area selection modes

To understand how to change the focus area selection mode on your camera, it is better to read the instructions. For entry level DSLRs like Nikon D3100 or Nikon D3300, you need to enter the “Shooting Menu” section, and advanced cameras have a switch on the back. Here, for example, is what the auxiliary display looks like on Nikon D600 and D610 SLR cameras.

We press the AF button at the base of the mount, and without releasing it, rotate the front and rear control wheels.

4. Autofocus scenarios and examples

Well, we learned a lot of technical information about what each of the auto focus and AF area selection modes are. Let's go through more scenarios and look at examples to better understand and assimilate the data presented earlier. The camera settings described below are taken from Nikon cameras.

4.1 Scenario #1 - Filming outdoor sports

What autofocus mode and type of AF area metering will we choose when photographing, for example, football? Let's start by choosing the right focus mode. Obviously, single-servo AF-S won't work, as we want the camera to focus continuously as long as the shutter button is half-pressed (well, or whatever button we assigned to AF). Therefore, we must use either AF-C or AF-A mode. Professionals want to take full control of the shooting process, so they switch to AF-C continuous-servo autofocus in such a situation.

What about AF area selection? Should we enable Single-point AF, Dynamic AF, Group AF, or 3D Tracking? Professional photographers shooting sports like football, basketball or outdoor hockey will turn on 3D tracking, allowing the camera to watch the athletes while the person is composing the shot. If it suddenly turns out that 3D tracking does not work correctly, it often makes mistakes, then you can switch to "Dynamic AF" with a fairly large number of focus points, especially if we are standing close to the scene. Group AF will only work well if we are standing very close to the subject. Here is a set of focus mode settings for the described cases:

1. Auto focus method: AF-C
2. AF area metering mode: 3D Tracking, Dynamic or Group AF
3. Custom Settings => Dynamic AF: 21 or 51 points
4. Custom Settings => AF-C Priority Selection: focus priority

4.2 Scenario #2 - Shooting people on the street

When we photograph people posing for us in nature on a sunny day, any of the focus modes should work well. If we chose AF-S, the camera will focus once as soon as we half-press Shutter, so we just need to make sure our subject doesn't move after focusing. By default, the camera will not allow you to take a photo in single-servo AF-S mode if the focus is not achieved.

If, however, we are shooting in AF-C continuous focus mode, then we just have to make sure that the focus is correct before pressing the button. Also, AF-A is good for shooting portraits.

As for selecting the AF metering area, it is more convenient to shoot with "Single-point AF" because the subject is stationary.

1. Modeautofocus: AF-S, AF-C or AF-A
2. AF metering area: single point
3. User settings => Priority selection for AF-S: focus priority
4. Custom Settings => AF-C Priority Selection: release priority

Probably not worth mentioning that we should always focus on the nearest eye of our model, especially if she is close to us.

4.3 Scenario #3 – Shooting portraits indoors

Photographing people inside a building in poor lighting can be a little tricky. If the room is dark, you can switch to AF-S single-servo focus mode so that the assist lamp will help us if necessary. If we have an external flash, the AF-S mode will turn on the red beam to adjust the focus.

In AF-C mode, this function cannot be used. And the AF-A autofocus should do the job, too, but professional photographers will prefer to turn on AF-S.

As for AF area metering, it is more convenient to use the center focus point for greater accuracy in low light conditions.

1. Autofocus mode: AF-S
2. Measurement: Single point AF
3. User settings => Priority selection for AF-S: focus priority

4.4 Scenario number 4 - photographing birds on the fly

Shooting birds is an extremely difficult genre of photography because it is difficult for us to predict their behavior and they often fly very fast. As noted above, when hunting it is better to select the Continuous Tracking AF (AF-C) mode, and the focus area is either Group AF or Dynamic AF from the 9th or 21st (I would like to take pictures at 21 points , but usually 9 pieces is faster). Professional photographers say they've tried 51 focus points and 3D tracking, but these modes are slower and less accurate than with fewer points.

One of the photographers told me that in 99% of cases he focuses on the birds on the central point, changing it only when the birds are sitting high on some branch. Once again, the central focus point will give the best result in most cases. If we are shooting small birds and there is no time to set the initial focus point, we can try the Group AF mode (if available on your camera).

1. Autofocus mode: AF-C
2. AF area metering: Dynamic or Group AF
3. Custom Settings => Dynamic AF: 9 or 21 points
4. Custom Settings => AF-C Priority Selection: release priority

4.5 Scenario #5 – Shooting landscapes and architecture

For these types of shooting, all focus modes are suitable, but it is more convenient to use AF-S, since we do not have objects to follow.

In poor lighting conditions, we will not be able to use the AF-assist illuminator function, because the distances are very long. In this case, you can mount the camera on a tripod and switch to Live View in order to focus on the bright object of our scene with a contrast method. If this does not help, one thing remains: turn off auto focus and focus manually.

When shooting landscape or architectural objects, we need to be more attentive to what our camera is focused on and remember that the need for a clear understanding of what depth of field (DOF) and hyperfocal distance is of particular importance.

One thing can be said about the AF area metering: we definitely need the “Single-point AF” mode to focus exactly on a specific point in our frame.

1. Autofocus mode: AF-S
2. AF area selection method: Single point AF
3. User settings => Priority selection for AF-S: focus priority

4.6 Scenario #6 – Shooting Large Animals

On a photo safari, when shooting large animals, professionals prefer to use the continuous AF-C tracking mode and the AF area metering method "Dynamic AF" or "3D tracking", both of which work perfectly. Animals are usually not as nimble as birds (although sometimes they can move even faster), so if we are shooting non-fast action, it is better to use Dynamic AF with more focus points or apply 3D tracking.

1. Auto focus mode: AF-C
2. AF area selection: dynamic focus or 3D tracking
3. Custom Settings => Dynamic AF: maximum number of points or 3D
4. Custom Settings => AF-C Priority Selection: release priority

Hopefully, the scenarios listed above will make it easier to understand when and how to choose one or another focus mode and focus area metering. Now it's time to return to the table above and check if we understood everything well.

4.7 Scenario #7 – Photographing small groups

Beginners often ask what mode to focus on when we shoot a group of several people. Before talking about autofocus mode, there are some important things to discuss. If we are using a standard focal length lens or a wide aperture telephoto lens, we need to keep in mind the distance to the subject. When we stand close to our group and shoot at f/1.4-f/2.8, it can happen that only a couple of people are in focus, and the rest are blurred, unless they are standing in the same plane. There are two solutions here: either stop the aperture to f / 5.6 or f / 8, or move further away to increase the depth of field. Or you can use both of these tips.

If we want to blur the background and shoot at a large aperture, we can only put everyone in a row, strictly parallel to the camera. Imagine how it would be necessary for people to stand if they pressed their heads against a flat wall - this is how our models should be positioned.

As for the focus modes, in the daytime they will all work well, but it is more convenient to use a single point focus.

1. Modesautofocus: AF-S, AF-C or AF-A
2. Measuring method: Single point AF
3. User settings => Priority selection for AF-S: focus priority
4. Custom Settings => AF-C Priority Selection: release priority

Note: As you can see, in all modes, the priority selection for “AF-S” and “AF-C” is set to “focus priority” and “release”, respectively. And that's why. By setting the single-servo focusing mode to AF-S and “focus priority”, we tell the camera not to let it take a picture if it could not focus. Professional photographers don't use AF-S very often, but when they do, they want the shot to be sharp.

For AF-C continuous-servo autofocus, "release priority" works great in most situations: the camera adjusts focus as closely as possible, but doesn't allow too long shutter lags, allowing the photographer to shoot when they want to. It makes no sense to think for the AF-C mode about what priority to set: release or focus. In "release priority" the camera doesn't care about good focus or bad (why autofocus then?), and in "focus priority" it won't let you take a good picture until the focus is locked. If we need the focus to be this precise, we switch to AF— Sthen. Just set this parameter as shown in the examples above and forget about them forever .

5. Tips for improving autofocus performance in low light

As noted earlier, in good, sunny shooting conditions, the cameras do an excellent job of autofocusing. But when photographers start shooting in low light, they face a lot of problems, especially when shooting indoors. Here are some tips to make the autofocus system work better when there is not enough light:

1. Using the center focus point. No matter how many focus points our camera has 9 or 51, we still focus on the center, and not on the extreme ones, if we shoot in bad light, because it works more accurately. There is usually a cross sensor in the center, which works better than any other points in our camera.

But then what to do with framing and composition if we have to focus on the center point? The solution seems to be to reassign the autofocus function from the "shutter" button on the camera to another one located on the back of the camera. Then you can focus on the subject and recompose the frame. Most DSLRs, including entry-level ones for beginners, allow you to do this. Professional DSLRs have a button (usually called “AF-On”) that can be enabled through the menu by selecting “AF-ON Only” in the autofocus activation settings. But we have to be careful after recomposing the frame, especially when shooting with a small depth of field at an open aperture. When we focus and then move the camera, the focus will definitely shift, and we need to be careful to keep our subject sharp.

2. Turn on the autofocus assist light function on the camera or on an external flash. Whenever you have to shoot in low light, this feature helps photographers. To activate it, you need to make sure that the AF-assist illuminator is turned on in the menu and the focus mode is set to Single-servo focus - AF-S.

3. Selecting contrasting objects and faces. Instead of trying to focus on a flat, monochrome surface, look for "contrasting" objects that stand out from the background.

4. Add some light or turn on lamps. Sounds simple, but if we're having trouble focusing, what could be easier than adding a little more light or turning on more lights in the room? One professional photographer told how he had to shoot dances at a party. There was so little light that I had to shine a flashlight on the models to focus. Then he approached the organizer and asked to turn on the general lighting in the hall - all the problems were solved by themselves, and he was able to take great photos.

5. Keeping track of shutter speed. We may think that we have problems with focusing, but we should not forget that the shutter speed should be sufficient for handheld shooting. Details about the rule for determining the exposure time using the formula B=1/(2*FR) are described in a separate photo tutorial on DSLR settings.

6. Using a tripod. By using a tripod, we can achieve more precise focusing in poor light without having to worry about camera movement.

7. Let's use the contrast focus feature in Live View. With the camera on a tripod, we can try focusing in Live View mode, which, as we remember, can use a more accurate method of focusing on the contrast of objects in the frame. Many professional photographers find that whenever they have to shoot with a tripod, they try to use contrast focusing because it gives the best results. And, in general, it is more convenient to focus in Live View mode, since the image on the camera screen is larger than in the viewfinder.

8. Useful thing - a bright flashlight. If our camera model does not have a built-in autofocus assist lamp, we use a bright flashlight and ask someone to shine on our subject to try to focus. As soon as the sharpness is caught, we switch to manual focus mode and turn off the flashlight, take pictures “with self-timer”. I met the advice of professionals to use a laser pointer to focus when shooting night landscapes (do not forget that if you get into the eye of a person or animal, you can burn the retina).

9. Using manual focus. Such advice does not correspond to the title of the article, but we must be able to manually focus and not be afraid to do this. Sometimes manual focusing will turn out even faster than in automatic mode. Many landscapes, macro shots, and architectural photographs are taken with manual focus.

Photo 13. Another landscape shot with manual focus. HDR of three frames. Camera Nikon D610. Lens - Samyang 14 / 2.8. Tripod Sirui T-2204X.

P.S. Dear friends, colleagues and guests of the site! If you think that the article can be useful to other photographers, I will be grateful if you share a link to it on social networks, on specialized forums, and publish it on your blog. Just ask to put an active link to the source! The wife spent the whole day to draw all these frames on the photographs ... It is impossible that her work was in vain. Thanks! Good luck, sharp photos to you.

Like any automation, auto focus does not always work perfectly. Sometimes, the autofocus system can focus on the wrong part of the frame that you want to focus on in your photo.

Don't get us wrong, today's DSLRs and mirrorless cameras are capable of focusing faster than ever before. However, to create truly creative and artistic photographs, you need to adjust the focus yourself.

In what cases will autofocus not work properly?

Your camera may fail to focus automatically when there is not enough light or when shooting solid-colored subjects, such as when photographing a brown dog in an open field. In this case, the camera simply will not be able to determine the point for focus.

In such situations, the lens will move back and forth, trying to fix at least on some point. If in this case, there is some kind of foreground object - a bush, a branch, etc., then, most likely, the camera will focus on it.

Moving subjects can be very problematic subjects for auto focusing. For such shooting, you need to make sure that you have selected the correct focus mode, only in this way there is a chance to make beautiful, clear and sharp images.

What focus modes should you use and when?

The first thing to decide is whether you want to use autofocus or switch to manual focus mode. There are several situations where manual focus is the best option. To make sure you're working in auto mode, look to see if the lens is set to AF and not MF.

Autofocus offers two different modes, one of which must be set on the camera. These are One-Shot AF (Canon) / Single-Servo AF (Nikon) and AI Servo AF (Canon) / Continuous-Servo AF (Nikon). One-Shot/Single-Servo is the best option for shooting still subjects. After the system focuses on the desired object, you can safely take your picture.

As the name suggests, in AI Servo AF / Continuous-Servo AF mode, the camera continuously focuses on the subject, this mode is more convenient for tracking the movement of the subject. In this case, you can take a picture at any point in the picture, even if the subject is out of focus. This is provided for faster and more productive work.

Many cameras offer another autofocus mode: AI Focus AF (Canon) or Auto AF (Nikon). In this mode, the camera automatically detects whether the subject is still or moving and switches to the appropriate mode accordingly.

Do not confuse the choice of autofocus mode with the choice of focus area, which can also be set automatically or manually.

What is the difference between autofocus mode and focus area?

The focus mode determines what how the lens will focus, and the autofocus area determines where the camera will focus. Focus areas may vary between camera models and manufacturers.

When working with a camera, the photographer has the opportunity to choose whether it will focus on one point, or on several. While looking through the viewfinder and holding the shutter button halfway, you will see how the camera focuses. When focusing on one point, you can move the point.

How many AF points should you use?

It all depends on what you are shooting. If you set the focus to multiple points, the camera automatically selects which ones to use to focus on the subject.

At the same time, if the subject is large enough, then you may not be satisfied with how the camera focuses. For example, when shooting a monument, the camera may focus on the legs of a statue, while you would like the focus to be on the face. In addition, in this case, there is a risk of focusing on foreground objects while the subject is in the background.

In the same time, auto focusing on multiple points may be more productive when shooting a subject against a solid background, for example, when photographing birds against a blue sky. The more autofocus points a camera has, the more accurately it will focus and better follow the subject as it moves through the frame. In other cases, it will be preferable to use multi-point focusing.

Of all available AF points, center point, provides the best accuracy. It is best to focus on this point, and then, after locking the focus, move the camera so as to compositionally create an attractive photograph.

When to use manual focus?

Manual focus may come in handy when the focal length remains the same. For example, when photographing a car race, you can automatically focus on the track, and then, when the car pulls up, switch to manual focus and, following the car, focus manually.

Manual focus is also the only option when the camera cannot concentrate on its own. Some lenses allow you to constantly adjust the camera's focus manually without having to switch from manual to automatic all the time.

How to focus with Live View

Live View focuses fine in manual mode. When switching to auto focus mode, don't expect miracles from your camera.

Auto focus

Auto mode in Live View may work differently with each camera model. Most cameras are capable of fast autofocus and a slower but more accurate mode with face detection.

Manual control

Live View helps with manual focusing, as you can use the screen to magnify part of the screen and fine-tune focus. This is especially useful for landscape and macro photography. The task of the photographer is to make a very fine adjustment, since the difference between sharp and clear can be significant.