Zone mode af. Camera focus modes

Autofocus, including tracking, in comparison with manual focusing, is the preferred setting. In the hands of an experienced photographer autofocus works much faster, and more importantly, the average amateur photographer can act. However, autofocus is not such a simple thing as it may seem at first glance, but it should also be said that this is already quite a deep jungle, which is far from immediate.

Let's take a look at how to use autofocus, as well as those subtleties that will allow you to effectively manage it and get the best possible result.

To begin with, I recommend that you re-read the pages of your camera's manual, which are dedicated to autofocus - this will be the best start. For a normal perception of the material, you need to know and understand where the main autofocus and focus points controls are located and how they work.

Autofocus Modes

Most cameras, including Canon and Nikon, are equipped with three types of modes: single, tracking and hybrid autofocus.

Frame or point autofocus

This mode is intended for photographing still scenes, for example, portrait, landscape, still life, etc. In this mode, when the shutter-release button is pressed halfway, the lens begins to focus on an object that is located within the selected focus point. After completing the sharpening, focusing work is blocked, which allows you to change the composition of the frame (when the distance to the object changes, focus is lost) and make a frame.

Understanding this topic, it is necessary to understand that the lens focuses not on the subject, but at a certain distance. It follows a very simple conclusion. If I focus on an object that is at a distance of five meters, then, accordingly, all other objects located at a distance of five meters fall into the zone of sharpness. In other words, after focusing and locking autofocus operation, keeping the distance to the subject, I can twist the camera as I like, getting the composition that I need, while not losing focus.

This method is very good in cases where the distance to the object is large enough and measured in meters. At close distances, especially when macro photography, the rearrangement of the frame, which may entail a change in distance of several centimeters or millimeters, leads to a noticeable loss of focus, which is even more critical with a narrow depth of field.

Servo AF mode

This mode is also called continuous, it is simply indispensable when photographing dynamic objects - animals, sports, car races, etc. As long as the shutter button is half-pressed, the autofocus is continuously working, thereby keeping the object in the zone of sharpness. Naturally, the autofocus lock, as in the previous version, does not occur, which is caused by the constant movement of the lens mechanism, which catches the focus after the movement of the subject.

The obvious conclusion is clear. In this shooting mode, you cannot change the composition. This is because the autofocus responds to an object located in front of a certain point of focus, if you change the composition, the object will be lost and the focus will be made on something else.

So, we understood what tracking autofocus is, now the last mode remains - automatic or hybrid. It was created in order to decide whether to block the autofocus or not. This mode, unlike other automatic functions of the camera, seems strange and useless to me, but this is my subjective opinion, it is possible that someone will find utility and convenience in it.

Priority trigger or focus

For many newbies, the existence of such settings will seem surprising. But they exist and do not pay attention to them, examining the autofocus, it is simply not possible. The first priority (descent) means that at the moment when the shutter button is fully pressed, sharpness is irrelevant, in other words, control of this is completely entrusted to the photographer. This mode is standardly enabled for servo autofocus.

Focus priority means that after the shutter button is fully pressed, the focus should be on specific or defined focus points. If it does not, then the camera does not allow to make a frame. This mode is usually enabled with standard settings in single-frame mode.

Contrast and phase autofocus, which one is better?

In digital cameras, manufacturers use two types of autofocus, as you already understood from the name, this is contrast and phase autofocus. It will be very good if we understand these concepts.

Contrast autofocus system

This method of autofocus is used in the so-called digital cameras and SLR cameras, but only when the “Live View” function is turned on. This type of autofocus does not require additional focusing sensors, since it uses only the camera matrix for focusing. The picture, which comes from the matrix of the camera, is analyzed by the processor of the camera for the presence of a change in contrast. If necessary, a more accurate focusing on the processor instructs the engine to slightly change the position of the objective lens in any direction. If after this manipulation, the image contrast is reduced, then the direction of movement of the lenses is reversed. The movement in the right direction continues until the contrast begins to fall again, having reached this limit, the processor tells the motor to return the lenses to the step at which there was maximum contrast. Reaching this value, the focus is considered complete.

As you understand, due to such features of autofocus operation (it is not known which way the engine should be rotated) a lot of unnecessary movements are performed. What leads to the main disadvantages of this focusing method is low speed, which does not allow using it on professional cameras. The second minus, maybe not so critical - increased power consumption.

The advantages of this method are simplicity of design and the ability to focus almost anywhere in the frame.

Phase autofocus

As you understand, manufacturers of photographic equipment have long responded to us and to myself the question of which autofocus to choose. Of course, the phase system won. Let's look at why.

This type of autofocus is used in SLR digital and film cameras. Here there is a slight interference with the optical image transmission system, so besides the main mirror, the camera is equipped with an additional mirror, which transmits part of the light to the phase autofocus module. Any light beam that passes through the beam-splitting prism and microlenses is divided into two beams, each of which is then sent to the autofocus sensor. If focusing is accurate, then the rays fall on the sensor in a strict distance from each other.

If the distance between the rays is less than the reference, then the focus is closer than necessary (front-focus).

If the distance is greater, respectively, the sharpness is induced further (back focus).

The magnitude of the shift indicates the distance from the ideal focus. Thus, the processor immediately receives data on which way and how much it is necessary to make an adjustment.

Phase autofocus sensors can be cross-shaped and linear. Linear, also divided into vertical and horizontal. The latter are sensitive to vertical lines (tree trunks, fence), and vertical ones are more sensitive to horizontal objects (horizon, road). Accordingly, cruciform sensors are universal, they are susceptible to objects of any shape. You can find out which sensors and where they are located from the instructions for your camera, but the most sensitive sensor is located in the center of the frame.

The main positive quality of phase autofocus is its speed, which makes it indispensable when shooting dynamic scenes. The main disadvantage is the complexity, bulkiness, the need for the finest alignment of all components, lower accuracy than the contrast autofocus and a small number of focusing points.

Hybrid system

There is also a third type of autofocus - hybrid. From the name it becomes clear that this is a combined system, including the qualities of both the systems described above. Such autofocus is used in mirrorless and some SLR cameras.

The essence of this system is that the sensors are mounted directly into the matrix. Thanks to this focusing occurs on the following system. At first, the basic focus induces phase autofocus, and then based on the data obtained, contrast starts to work. At the same time, the slowness of contrast autofocus is reduced by more than 75%. Phase autofocus does not require such precise alignment, and the whole system takes up much less space.

Having examined all the technical aspects of autofocus work, I want to conclude by saying a couple of words about those factors that also affect its work:

Aperture lens.  Here, as always, the higher the luminosity, the better the autofocus works.

Focal length.  Here, everything is quite confusing, but if in a nutshell, the larger the focal length, the more visible any autofocus miss. In addition, there is shake, breathing and other factors. I conclude that the longer the focal length, the worse the autofocus works.

Detailing and illumination of the image.  The less detail and light in the area of \u200b\u200bthe focus point, the worse the autofocus works.

The photographer himselfor rather your ability to use your technique. If a person skillfully addresses, then everything works, if it is careless and not correct, then even the most modern autofocus system will miss.

The most important thing in your work with autofocus is practice. The correct weighted approach to the work of automation will give you the opportunity to quickly and accurately focus. What is actually necessary.

Successful photos to you!

About how the autofocus is arranged in modern SLR cameras. But any type of focus has several modes of operation. The photographer can choose from them the most suitable for a particular shooting situation. So what are the autofocus modes? When should one of them be used? Let's see ...

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

Let's start with a simple one: how do the focus modes switch on Nikon cameras?

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

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

• Now that autofocus is on, we’ll select the desired mode.

On advanced Nikon D7200 level cameras and above, there is also a special button for selecting autofocus modes. It is combined with the on / off lever of the autofocus. It is necessary, while keeping it pressed, to twist the rear wheel of the camera control. Although in words it looks complicated, in fact, this method of switching focus modes is very fast. The involved focus mode will be displayed in the viewfinder and on the camera screens (depending on the model, on the top and main or only on the main).

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

Single autofocus. AF-S

Single-shot autofocus, or AF-S (Auto Focus Single), can be called the basic, basic autofocus mode. Usually, it is used by default. In this mode, the focus is as follows:

By pressing the shutter button halfway, you activate the autofocus system;

The camera focuses at the selected (by you or automatic) point, and then notifies the user about it with a sound signal;

After that, the focus is locked at a given position until the shutter button is pressed to the end (and a frame is taken) or simply released.

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

• AF-S mode is well suited for shooting static scenes. Suppose you are shooting a landscape, still life or a person posing for you. In this case, the focus object does not move anywhere. So, you can focus on it once, and then quietly shoot or reassemble the frame, holding the shutter button halfway down. An important caveat: after the focus has been made and the camera has given a signal about it, you cannot change the distance between you and the object you are shooting (approach or depart). This will lead to the fact that the subject is again out of focus. This is especially important when shooting portraits on high-aperture optics: there the change in the distance even by a couple of centimeters is threatened by the fact that the model's face is blurred. If, however, the distance was broken, it remains only to focus again.

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

AF-S mode is perfect for shooting a staged portrait. The main thing is to remember that after focusing it is impossible to change the distance between you and the subject, so as not to lose focus. After focusing do not waste time in vain - immediately shoot!

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

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

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

Continuous autofocus. Af-c

Tracking focus mode, or AF-C (Auto Focus Continuous), works differently. By pressing the shutter button halfway down, you turn on the auto focus. Now it will “track” the subject at the selected focus point until a picture is taken or the shutter release button is released.

Continuous autofocus is perfect for shooting fast moving objects.. Use it for shooting sports events, children's games, frolicking animals. There is a mass of diverse movement in the world - don't miss it! At the same time, modern technologies of 3D tracking and dynamic selection of focus points 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 frame recomposition after focusing.  The favorite technique of some photographers is to focus on the central point of focus, and then, when the focus is locked, recompose the frame as you like. It is inconvenient to use this technique in continuous autofocus mode, because focus will be lost when the frame is rearranged. The only option is to rebuild the frame while holding 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 will not run away from the focus at the time of shooting!

AF-A mode

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

Autofocus operation modes when shooting via Live View

From a recent article on autofocus types, we know that when focusing through the viewfinder and through the Live View screen, completely different mechanisms are involved. When focusing through the camera screen uses a type of autofocus, called contrast. He has his own modes of operation.

Single-shot autofocus AF-S

This mode is similar to the mode of the same name, which is available when focusing through the viewfinder of the camera. When you half-press the shutter button, the camera focuses at the selected point. After the success of the operation, the focus is locked until a frame is taken or the shutter button is released.

But continuous autofocus AF-F  works a little differently than AF-C. Focusing is not made when the shutter release button is half-pressed, but when it is released. That is constantly. When the shutter release button is pressed halfway, the focus is locked. This method allows you to constantly monitor the subject, without losing sight of it for a second.

Lock the autofocus button AE-L / AF-L

AE-L / AF-L button on the Nikon D7200

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

As you can see, the choice of functions available for this button is quite wide. In addition to locking AF or exposure to it, you can assign other parameters.

So, we figured out the modes of autofocus. But this is not enough to learn how to use the camera's automatic focus system for one hundred percent! One important question remains: how to tell the camera which object exactly you want to focus on? In the following lessons we will learn how to work with zones and focus points. Stay with us!

Modes and focus settings of the camera can easily be confusing for beginners. Corrosive study of the camera’s instruction manual can be quite tedious. In addition, it can not always give the proper result the first time. Where do you start mastering focus modes? Let's take a look at the basics and make the process of studying camera focusing modes easier.

The photo above illustrates the most important aspect when deciding on a focus mode — a conscious choice. I consciously focused on the eye of the model closest to me. Not on her hand in the foreground or background. And certainly not in the background. I chose exactly what I would like to make the sharpest in the photo. It was not the camera who made this decision, but me. This is the secret of choosing the focus mode - be aware of your choice.

Building on this principle, we will go through the focusing modes available in your camera and see which one will be the best choice in a given situation.

First of all, we will need to consider three interrelated aspects:

A) Existing focus modes - such as Single or Continuous (Servo / Continuous).

B) How do you activate autofocus (AF):

• By pressing and holding the shutter button, or
• Pushing a button . The so-called method of focusing the back button.

In this case, your choice will determine how you will use the Single or Continuous autofocus mode.

C) Selection of the AF area  - how the points you have selected will be grouped together.

In photos with a shallow depth of field, you must clearly select the point to focus on. Your decision must be conscious at each stage of the creation of the image.

Focus Modes

No matter which camera maker you use - Canon, Nikon, Sony, Fuji, Pentax  or Olympus  - focusing modes can be divided into three types:

• Manual focus  - You do all the work of focusing the camera yourself.
• Frame focus (Single / One-shot focusing mode / AF-S) - The best choice for shooting static objects: the camera focuses and locks the focus.
• Continuous focus (Servo / AI Servo / Continuous focusing mode / AF-C) - The best choice for shooting moving objects - the camera continuously adjusts the focus.

The choice between Single and Continuous focusing modes becomes more convenient when using the Focusing method with the back button, to which we will return.

The choice of an AF area can vary from a single point, to their union in the area. Variants of this grouping vary depending on the brands and models of cameras. The selection of the AF area affects how quickly the autofocus can focus on a specific area of \u200b\u200bthe image you have selected.

Manual focus

Compared to various autofocus modes, manual focusing is extremely simple - you rotate the focus ring until the subject is in focus. That's all.

Manual focus is preferred in several cases:

• When shooting video when you can not use autofocus. Although, now more and more models that support autofocus when recording video appear on the market, autofocus does not always work correctly in them. So for video, manual focus is still relevant.
• Photographing architecture, food and other static objects in which you are most likely to work with.

Cameras offer various ways to help with manual focusing. For example, you can magnify an image on the LCD screen in Live View mode or use the focus peaking function (a bright-contrast feature that highlights the edges of a focused object). If you plan to use manual focus, check what your camera has to offer you in this area.

Single-shot focusing mode / AF-S

In single frame focus mode, the camera focuses and stops. Focus locks as long as you hold down the shutter button. If you decide to refocus, you will need to re-activate by pressing the shutter button or the AF-ON button again.

This autofocus mode is the complete opposite of Continuous Autofocus, in which the camera constantly adjusts the focus.

The function (with a special lamp or camera flash) works only in frame mode. In continuous focus mode, this feature is not available. This can be extremely important when shooting in low light conditions.

The autofocus frame by frame mode is also called the Focus Priority mode, because the camera's shutter will not work if the image is out of focus. However, this can be changed using custom camera settings.

Continuous focusing (Servo / AI Servo / Continuous focusing mode / AF-C)

This focus mode is ideal for capturing moving subjects. The camera tracks movement and constantly adjusts focus. Most modern cameras are equipped with predictive autofocus, which allows the camera to be more accurate when shooting moving objects - it more “guesses” where the object will be at the time of shooting.

Continuous focusing has a potential side effect. When focusing in low light conditions or on low-contrast objects, the camera's autofocus can “walk” back and forth before it focuses. When shooting static subjects, this can be a problem, since the shutter may work when the subject is not entirely in focus.

Therefore, for portrait shooting or shooting static subjects, the frame-by-frame focusing mode is most likely to be the best choice, since in it the camera will give the best results in focusing and fixing the focus.

Continuous focus mode is also referred to as the Shutter Priority mode, because the shutter is triggered at any time as soon as you press the shutter button, regardless of whether the subject is in focus or not (This can be changed using the camera's custom settings).

Intelligent Focusing / AI Focus (Canon) - Auto / AF-A (Nikon)

In this mode, the camera uses frame-by-frame focusing if there is no movement in the scene being shot. As soon as movement appears, the camera switches to continuous focus.

How do you activate autofocus?

You can lock the focus using the shutter button or

You can lock / activate focus using the AF-ON button.

The choice between these two methods of starting and locking autofocus will determine which focus mode is more appropriate for your shooting style.

Focusing with the shutter button

The most common way to start and lock autofocus is by pressing the shutter button halfway down.

A side effect of this method is that now your focusing method is associated with the actuation of the camera shutter. If you think about it, the time taken to take a picture is not really related to focusing. These are separate processes.

Focusing with the back button (FZK) / AF-ON button

Using the AF-ON button, you can separate the focus and shot functions. Thereby releasing the shutter button from the function of starting and locking the autofocus.

Check the instructions for your camera to find out which user settings allow you to reassign the start and lock AF functions to the AF-ON button.

When choosing the focusing method with the back button - as a rule, using the AF-ON button - the way of starting and locking the autofocus will change. Instead of half-pressing the shutter button to start and lock the autofocus, you need to press the AF-ON button, and when the camera focuses, release it, thereby blocking the autofocus.

Usually, with FZK, continuous focus is used in combination with start / lock autofocus using the AF-ON button. Thus, you can constantly monitor the movement, and open the shutter at the right time. Or you can shoot portraits (or still objects) by blocking autofocus, simply by releasing the AF-ON button. Simply put, to take a portrait, you activate the autofocus by pressing the AF-ON button, and when the camera focuses, release the AF-ON button. The camera will not refocus until you activate the autofocus again.

In some cases, this method has certain advantages.

For example, if you are photographing an event where awards are presented, and those awarded are each time in the same place, the FZK method works very well - you do not need to refocus each time, because the camera and lens are focused at the same point as before by this. In addition, you do not have to constantly hold your finger on the AF-Lock button, because with the FZK, the focus is locked when you release the AF-ON button.

This is the elegant ease of use of the FZK method. However, no matter how hard I tried, I could not get used to this method, so I still use the shutter button to lock and hold the autofocus.

Select AF area

All cameras allow you to group autofocus points in an area, as an alternative to using a single AF point. How the autofocus areas will be located and how many focus points will be included in them depends on the specific camera model. Look in the instructions for your camera to clarify this point.

The choice of a point or area depends on which autofocus sensors are used in your camera: a cross type or not.

Cross-type sensors are capable of focusing on both horizontal and vertical lines. Usually only a few sensors in the center are cross-type sensors.

This circumstance should be taken into account when choosing AF points.

That is why AF sensors that lie outside the central region are in many cases not so easy to use. Of course, in this case, an excellent option may seem to be autofocus lock, followed by frame re-compositing. But this technique also has disadvantages.

Let's return to the idea of \u200b\u200bconscious choice:

If you are photographing a scene with moving subjects, especially one where objects move erratically, it is better to select an area, rather than a separate AF point. Such a choice can also be useful if you allow the camera to independently select the AF point.

For shooting portraits, it is preferable to use the focus on one point and choose the point where you would like to focus. This is usually the eyes of a model, or her closest eye to you.

If, when shooting a photo posted at the very beginning of the article, I would choose the AF area, rather than a specific point, then most likely, the nearest hand to us would be in focus. Not the best choice. So the decision about where to focus should have stayed with me.

Lock focus and frame rearrangement

If the subject is not in the center, then you have two options to focus and block the focus:

• Use appropriate, off-center AF points (but if they are not of the cross type, you may encounter some problems), or
• Focus on the center point, block the focus and re-arrange the frame.

Another situation where you can use the focus lock and frame rearrangement techniques is when there is strong backlighting in the scene and the camera has trouble focusing automatically. The photo below is a typical example of such a case:

I took this picture right in front of the sun, and I was nearly blinded by the bright light and the sweat that filled my eyes - so I had to take a series of shots, moving a little to the side. All this was done in order to be sure that I will receive at least a few clear pictures.

I pre-focused on the pair, then locked the autofocus and rearranged the frame. The depth of field at f / 7.1 for this photo was enough to eliminate any focusing error caused by the rearrangement of the frame.

So we come to the potential problem of focus-blocking and frame rearrangement — when you move the camera by changing the composition of the frame, you risk shifting the focusing plane too much.

If your lens has a perfectly flat focusing plane, then as soon as you move the camera even a small distance to change the composition of the frame, the focusing distance will, of course, remain the same, but the focusing plane will shift after the camera.

So, if you change the composition so that your subject is now not in the center of the frame, the focusing plane may be slightly behind it. As a result, you get a photo that looks a bit blurry (this may look like the result of lens back-focus, but the reason is completely different here).

Offsetting the focus plane when using the focus blocking method and frame rearrangement does not pose a serious problem, for example, when taking a close-up portrait on a telephoto lens. In this case, moving the camera away from the eyes of the model to change the composition will be insignificant and will hardly affect the focusing plane, and the DOF will most likely easily cover any minor focus flaws.

But at an open aperture when using a wide-angle lens, this becomes a potentially serious problem: when you turn the body to change the composition, the focusing distance cannot remain correct. It directly depends on how much you move the camera, what kind of depth of field you have, and also on the curvature of the focal plane of your lens.

Taking into account this circumstance, it would be a great idea not to get too carried away with the technique of locking the focus and re-arranging the frame.

If you are sure that your off-center AF points are accurate enough, it is better to use the corresponding AF point instead of recomposing the frame.