Checking the accuracy of autofocus and fine-tuning it. How to use manual focus on a digital camera lens

To understand which autofocus mode to choose, you must first understand what you are photographing. Autofocus modes and settings on all cameras are about the same. They may differ in name and be managed differently, but the principle is the same everywhere. So what is autofocus?

First, make sure you have autofocus turned on. On advanced cameras (Nikon / / D7000 / D7100) there is a separate switch on which there is an M mode (manual focus) and some other modes - different autofocus, or just AF.

The M (Manual) mode works the same way cameras did in the 50s, that is, without autofocus. If you do not have such a switch, then the autofocus modes on your camera are controlled through the menu.

In addition, autofocus lenses with a built-in motor (AF-S) also have an autofocus switch, very often marked M / A - M. Make sure that the lens is not in manual mode either. Do not confuse the AF-S lens type with the AF-S autofocus mode, they are different things, although they are called the same thing.

Autofocus modes are as follows:

AF-A (Auto). Automatic mode, in which the camera decides for you how to focus. If you are not sure which mode you need, choose the automatic mode.

AF-S (Single). Mode for static scenes. In this mode, the camera focuses once when you press the shutter button to the middle, and that's it. The camera no longer focuses until you release the button. Great for landscapes and portraits.

AF-C (Continuous). Tracking mode, where the camera constantly follows the subject and adjusts autofocus continuously until you release the shutter button. Turns on when you press the shutter button halfway. This mode is great for photographing wildlife, sports, and fast-moving children.

In the Custom Settings Menu, in the Autofocus section, you can find AF-S / AF-C priority selection.

Release is the shutter release immediately, even if the image is not at all in focus. I hardly remember ever having sharp shots in this mode.

Focus- The shutter only works when the image is strictly in focus. This is very slow and you risk missing a frame.

I recommend value release+focus for AF-C, it's something in between. Even if the first frame is out of focus, the next ones will be much better in continuous shooting. In this case, you will not lose the first frame, although it will be a little blurry. Focus is good for AF-S because nothing moves in the frame.

In addition, you still have to choose the type of autofocus area.

Nikon usually offers three options:

Conditionally, the areas can be divided into two types:

Multiple sensors (AF-Area). Focus information comes not only from the sensor you have selected, but also from the surrounding points, and the surrounding sensors are not highlighted in any way. For example, on the Nikon D7000, you can select a zone from 9, 21 or 39 points. Usually, the faster something moves in the frame, the more area is required. To be honest, I don't use these zones, I prefer 3D-tracking.

3D tracking. This mode can be on some models along with a white rectangle and a crosshair, on other models somewhere else, for example, when choosing the size of the autofocus area. As the name implies, this is a tracking mode, and when tracking, not only the distance to the object is taken into account, but also the color. You choose a focus point, autofocus clings to what is under this sensor, and then starts to follow it if the subject moves or you turn the camera.

The fundamental difference between AF-Area and 3D-tracking is that in the first case, the camera focuses on what falls into the selected autofocus area, and in the second case, the camera itself moves the area behind the object, switching autofocus sensors. Therefore, in 3D mode, it is very convenient to focus on something specific, then move the camera to frame it differently, but autofocus will still focus on what it was aimed at initially. This differs from the AF-S mode in that AF-S is not aware if the object moved further or closer during framing, or even flew out the window.

In addition, 3D tracking can even replace single focus point selection. Instead of going through the points with the selector until you get to the one you need, you can simply visit the center in 3D mode and then crop it as you need, while the camera will keep focus on the object, moving the focus point, switching autofocus sensors. The object, at the same time, will not be able to escape from autofocus.

Keep autofocus in auto mode (AF-A, white rectangle), this mode will work fine in most situations without your help. If the work of autofocus did not suit you in any particular case, then start thoughtful settings.

That's all autofocus.

When setting up the camera before shooting, along with shutter speed, aperture and ISO value, you need to set the focus mode.

Nikon cameras have many various options focus. You can select both modes and focus areas.

Focus modes:

AF-S (auto focus single)- In this focus mode, the camera starts to automatically focus when the shutter button is pressed halfway. In order to focus again, you need to release the button and press halfway again. This mode is suitable for static scenes.

AF-C (auto focus continuous)- This is the tracking focus mode. When the shutter button is pressed halfway, the camera constantly tries to focus. It monitors the change in composition or the movement of objects. It is very convenient to use this mode in dynamic scenes.

AF-A (auto focus automatic) is the automatic mode. The camera decides which focus mode to use. She chooses between AF-S or AF-C. Many people prefer to use this mode, and novice photographers may not even be aware of the existence of other focus modes.

M (MF - manual focusing) is manual focus. It turns on near the lens mount in cameras with a motor, and in the camera menu in cameras without a motor. This mode involves manual focusing by rotating the corresponding ring on the lens. For newbies this method focusing may seem complicated, but professionals use it mostly. Manual focus mode is hallmark professional cameras from compacts (soap dishes). Auto focus does not work correctly in many situations, and in this case only manual adjustment can help.

The picture shows the focus point at which focus has been achieved.

Attention: manual mode provides the ability to focus on only one point.

Some Nikon cameras have a built-in rangefinder. It shows the photographer where to turn the focus ring to focus on a specific subject. Many older lenses that do not have auto focus have focus dials.

Any Nikon CZK camera has a pointing accuracy sensor. It looks like a green circle in the lower left corner of the viewfinder. When it lights up, it means that the sharpness is normal for the selected focus point. This indicator is a great help when working with older lenses, such as the Nikon 100mm F/2.8 Series E MF

Advanced cameras have fine focus adjustment - release priority and focus priority. It is available in AF-C mode.

The most commonly available settings in AF-C mode are:

1. FPS - frequency - for the camera, shutter release is more important than focus accuracy. It got the name release priority
2. FPS frequency + AF - shutter is priority for the camera, but focus is also taken into account.
3. Focus - Focusing is the top priority for the camera.

These priority settings determine how the camera will act. She can focus first and then take a picture, or take pictures, regardless of the quality of the focus. There is also an average value.

Note:

More budget Nikon models do not work in shutter priority mode ( release priority) in AF-S/AF-C modes. They operate in focus priority mode. Such cameras cannot quickly take a picture. Even though the shutter button is pressed all the way down, the camera will not take a picture until it is sure that the focus has been achieved correctly. This is a very serious flaw that occurs in Nikon D40, D40x, D3000, D60, D5000, D3100, D3200 amateur cameras.

To combat this inconvenience, you can shoot in manual focus mode (M). Some lenses have an M/(M/A) mode. It allows you to take instant pictures with manual focus adjustment.

Note 2:

Nikon professional cameras, shooting in AF-C mode, work with Release Priority. This mode allows you to take pictures by pressing the shutter button fully, whether the camera is in focus or not. Some cameras have this mode built in by default.

Live View (live view)

In this mode, focusing is much slower. The decrease in focusing speed reaches tens of times. Live View mode focuses on contrast. Some cameras have two focus modes in Live View. In the first, the camera focuses on contrast, as in amateur cameras. In the second, during focusing, the camera turns off Live View, focuses, takes a picture, and turns Live View back on.

Focus points and areas

Each camera has a different number of points and focus areas. For the focus itself, the module is responsible, which is located under the mirror of the camera. This module is engaged in the calculation of phase values ​​and gives commands for focusing. Usually, focusing modules have several points on which focusing is calculated. By 2012, Nikon cameras have modules with three, five, eleven, thirty-nine and fifty-one focus points. The ease of use of the camera and the accuracy of focusing depend on the number of points.

Working with focus points is carried out in the focus area mode - AF area mode.

• Auto (auto-area AF), automatic focusing on the nearest object that falls into the area of ​​the white rectangle. Focusing is performed on all available points.
• Dynamic focus (dynamic-area AF). It works on one point, but the setting takes into account the values ​​of a number of points standing near it.
• One point (Single Point AF). This type of focusing is performed only on one point.
• Additional: multi-zone selection or 3D-tracking. These settings are not available in all chambers.

Single-point AF-S focusing

Advice:

In amateur and advanced cameras, there is a programmable button on which it is very convenient to set the focus mode switch for quick adjustment. On professional cameras, there is a special focus mode switch, which simplifies the work and makes it faster.

Note:

Some cameras can show which points have been focused. Focus points are marked with square markers. This feature is only available on professional (D200, D300) and full frame cameras. This mode is convenient because the focus points are scaled, so you can easily assess the quality of focusing. In amateur cameras, such a check can be performed by zooming in on the picture in playback mode and scrolling it with the selector to the desired point. Sometimes the camera does not show which point was in focus. In this case, you can use ViewNX. it comes with the camera. You can view the focus points in greater detail on the computer display.

Note:

Some Nikon cameras in automatic mode do not allow you to change the area and type of focus. Other modes allow you to customize everything the way you want.

Single point focus in AF-C mode

Looping focus points

This feature allows you to move the focus point in a circle. For example, if the rightmost point is selected, then to move it, you need to press the selector in the appropriate direction. This function allows you to quickly switch focus points.

Focus area width

Some cameras, such as the Nikon D200, allow you to expand the focus area by reducing the points. For example, a camera with 11 focus points switches to 7-point mode, but the focus area expands (creates 7 wide areas). In the viewfinder, the zones will visually appear wider, which can sometimes make focusing easier.

Fine-tuning (adjustment) focusing

It happens that the camera erroneously focuses when focusing behind the subject or in front of the subject. This is called back focus and front focus, respectively. To correct this shortcoming, some cameras have an adjustment. This setting is not available on all cameras. Nikon D300, D7000, D300s, D700, D3(s,x), D800(e), D4 have it.

"Dark" lenses and focusing

Almost all Nikon cameras use auto focus without problems only with lenses whose aperture is no darker than F / 5.6. You can read about it in the instructions. With darker lenses, autofocus may fail. For example, Tamron 28-300mm F / 3.5-6.3 XR Di VC LD Asph (IF) Macro will not work correctly when shooting with aperture F / 6.3. The use of teleconverters also affects autofocus. They lower the effective aperture value. Only a few models can work with dark lenses up to F8.0, such as the Nikon D4, although it does not guarantee accuracy at full aperture.

Cross-shaped and regular focus points

There is no noticeable difference between cruciform and regular focus points, but it is believed that cruciform ones do a better job with the task assigned to them.

Focus illumination

Nikon cameras have a special llama that helps you focus in low light conditions. The lamp simply illuminates the subjects, thereby helping the autofocus adjust the focus. Sometimes best result can be obtained using the red flash spotlight.

Note:

Many Nikon cameras do not turn on focus illuminator when single point focus mode is selected and a non-center point is selected.

Nikon flagship cameras such as Dh, D2hs, D2h, D1, D1x, D2x, D2xs, D3s, D4, D3, D3x are not equipped with backlights at all.

Single-point focusing in AF-S mode

For those who do not understand everything?

If given material hard to comprehend, just switch your camera to AF-A and set it to display a rectangular focus area. For daily, home use, the automatic mode will do its job just fine. Besides, in professional photography the use of precise settings is not always justified.

Conclusion:

Using manual focus settings helps you achieve the desired result faster. In order to understand the difference between the focus modes, you just need to try them all and see how they work and what they affect.

Based on materials from the site:

Adjusting Canon's autofocus is a simple process that consists of several steps to check focus accuracy and make adjustments if necessary. In order to present the material as best as possible, I use part of the answer from Canon technical PR Chuck Westfall, who answers questions from users on TheDigitalJournalist online resource 12 times a year.

It's unfortunate, but the accuracy of the autofocus system is really a big problem for Canon. Here, technical flaws in production and cases of incompatibility are possible. In general, the incompatibility of initially compatible parts is strong philosophical theme, but this phenomenon sometimes happens, and not only with Canon.

Perhaps, due to a pronounced problem, an autofocus adjustment system was developed, which, of course, is very, very convenient! This feature allows you to adjust almost any working lens! It's great! Previously, in order to align the kit, you had to carry the camera and lens to an authorized service center. This was a huge problem for people from small towns, where such a service center simply did not exist.

Now, autofocus correction has become affordable and convenient, and our task is to figure out how to use it.

Before getting down to business, I will say a few more words about the adjustment process. In short, in order to determine the accuracy of the lens, you need to take a series of shots, thanks to which it becomes clear whether autofocus hits or misses. Misses can be of two types: focus point overshoot and undershot, back focus and front focus, respectively.

If everything is fine, then you forget about this article and enjoy life. If you find mistakes, then you need to understand what they are and make the appropriate correction to the camera, which, by the way, does not change the factory firmware. This type of correction works as follows: the camera receives not one command (to focus), but two, the second command is to move the focus point back or forward by a certain amount.

Such autofocus adjustment can still be divided into two types according to autofocus misses. In the first case, the camera misses with all lenses equally, and in the second with each lens at a different distance.

Both types of settings are completely different. Unless it's time consuming in the presence of a large fleet of lenses, in this case the first setting option will be faster.

Let's finish the long introduction and go directly to the autofocus adjustment, which, by the way, was written by the aforementioned Chuck Westfall.

How to set up autofocus on canon?

• set the camera on a good sturdy tripod;
• set the correct target with which to check the autofocus. You can download it. Target characteristics and location in detail described in the article "";

• sufficient homogeneous light should hit the target;
• the distance to the target must be at least 50 times the focal length of the lens. For example, for a lens with a focal length of 105 mm, the target should be located at a distance of 5.25 m (105 mm x 50 \u003d 5250 mm \u003d 5.25 m);
• the lens must be set to canon autofocus;
• camera focus mode - One-Shot AF;
• the test requires a central focus point;
• test shots are taken with the maximum aperture;
• use aperture priority mode (Av) or full manual mode (M);
• proper exposure is essential for a successful test;
• use the highest possible ISO value;
• if the lens has a stabilization system, then be sure to turn it off;
• use a cable release or shutter release timer to prevent shaking;
• an excellent result will be given by the included function of the preliminary lifting of the mirror;
• you need to take three series of shots that will use autofocus adjustment with values ​​from -5 to +5. The series will be as follows: 3 shots in a row with a value of -5; three snapshots in a row with values ​​of 0 and the last 3 snapshots with -5;
• view the photos you have taken on a calibrated monitor with a scale of 100%;
• repeat a series of test shots with different autofocus adjustment values ​​and thus achieve the sharpest photos;
• enter the resulting maximum sharp adjustment values ​​in the corresponding menu of the camera.

Before checking and adjusting autofocus, I recommend that you read the recommendations below, which will allow you to conduct tests even more accurately:

Eliminate the angles between the AF test target and the optical axis of the lens. The presence of such angles greatly reduces the stability and efficiency of autofocus. It is worth remembering that the autofocus sensor digital camera assembled from a large number of linear groups of pixels. Focusing on a target line at an angle to the optical axis of the lens may result in only a few pixels from each group being able to identify the target. The ideal test conditions would be a complete match of the contrast part of the target to the entire area of ​​the central autofocus sensor.

To get the best possible test shots, manually reset the focus before each shutter release. To do this, set the lens to infinity. Only after completing this procedure, focus.

If you shoot the same groups of pictures, most likely the photos in them will be slightly different. This is a normal situation due to the tolerances of the camera's autofocus system.

For the record, the autofocus adjustment of lenses becomes stronger, the longer the focal length of the lens.

You should be aware that the autofocus adjustment of a zoom lens will be relevant on this lens only at the focal length value at which you conducted the test. In other words, when testing a 28-70 lens at a focal length of 50mm, the adjustments you make will only work at a focal length of 50mm. Manufacturer in this case recommends adjusting such a lens at the maximum usable focal length.

It may happen that for a particular lens-camera pair, the autofocus setting will not be effective. In this case, contact an authorized service center for adjustment on special stands.

You also need to know what this moment there is no official system for adjusting autofocus. The technique described above is the one by which a positive result was achieved in more cases. Therefore, if you have come up with a more effective or faster technique - use it!

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Properly selected autofocus settings largely determine the success of shooting. For static shooting, one mode is recommended, for dynamic objects - a completely different one. There are a number of other points that can affect the result. So let's try to understand the intricacies of autofocus modes.

Auto Focus Modes

Switching between automatic and manual modes occurs using a selector. Pictured is Nikon D800.

AF-S mode is responsible for single-frame tracking autofocus - press the shutter button halfway, after successful focusing, you can press the button to the end and get a picture. This mode is optimal for portraits, landscapes, nature, that is, for everything that is still in the frame.

AF-C mode, on the other hand, continuously tracks the subject. When the main camera button is half-released, the system starts to track the movement of the object in the frame, correcting the focus.

AF-A mode is a hybrid option that automatically switches the camera from AF-S to AF-C and vice versa. The system automatically determines whether the object is moving or static. This mode is usually found in cameras entry level.

Autofocus settings are not limited to this, you can set the priority of the shutter button, focus or hybrid options, and even change the autofocus zones.

Autofocus zones

The multi selector is a jack of all trades, among other things, it is responsible for quickly changing the focus point.

Consider the operation of autofocus zones using the Nikon D800 as an example. The simplest option is single point. Basically, the mode is used to shoot stationary objects, allows you to select the desired focus point using the selector. In AF-C mode, the camera will correct autofocus if the subject moves.

The dynamic option can use 9, 21 or all the focus points that are in the D800 (51 points). When set to AF-S, the mode has no effect, switching to the previous state. Dynamic AF is exclusively for AF-C mode. The principle of operation is as follows: we select the initial focus point, if the subject moves around the frame, then the neighboring points will connect to the process and will track its movement and adjust the focus. The number of points can be chosen.

The 3D tracking mode deserves special attention. In it, having selected a focus point, the system will move it depending on the movement of the object across the entire field of the frame, using the maximum available number of focus points. This option Ideal for shooting fast and erratic subjects.

The last mode is automatic selection of the autofocus area. In it, the camera independently selects the subject in the frame and the focus point. In AF-C mode, it will correct focus as the subject and/or camera move. The option is not always suitable, since you will have to completely rely on the choice of camera, and as practice shows, the tasks of a photographer are often different from choosing automation.

Manual focus

The most advanced NIKKOR lenses, along with the familiar M and M / A, support autofocus priority mode, A / M.

In previous articles, we have mentioned manual focus lenses. So, using them, it is not necessary to adjust the autofocus settings, but it’s definitely worth switching to the focus point selection mode, i.e. single point. This is necessary so that when focusing on an object, the focus indicator values ​​\u200b\u200bare shown in the viewfinder.

In the case of autofocus lens models, it is enough to move the focus selector on the camera to position M, then calmly rotate the focus ring. Let us clarify that, using lenses with a built-in ultrasonic motor (SWM), it is possible to interfere with the autofocusing process of the system at any time, however, there are exceptions, we recommend that you read the instructions before using any technique.

On the lens barrel, you can find M / A mode, which gives priority to manual focus, while A / M gives preference to automatic mode. All classic lenses with the designation AF or AF-D use a drive in the camera or a “screwdriver” to work, in their case it is impossible to interfere with the autofocus process, otherwise this may lead to damage. Nuances are everything.

There are subtle settings that we have not touched on up to this point, but this does not change their significance. So, shooting in AF-C mode, you can set the priority when pressing the camera shutter, for example, give it to focusing on the subject or pressing the button itself. There is a third option, combined - release + focus. In it, the camera gives priority to the shutter button, given the focus. When continuous shooting is used, some frames may be out of focus for one reason or another. But at the same time, in order to more accurately focus on the object, the camera will slightly reduce the burst speed.

For AF-S (static shooting) mode, there are only two setting options: shutter priority or focus priority.

Illustrations provided

What should you do if you get fuzzy footage on a regular basis? Is the technique to blame or is it your actions? This article will help you figure it out. In it, you will learn how to check the focusing system of the device for accuracy and adjust it to get sharp shots.

Nikon D810 / Nikon 85mm f/1.4D AF Nikkor

I would like to say right away that in most cases it is not the camera that makes the mistake, but the person working with it. So, for starters, it’s worth looking for the cause of errors with focusing in your own actions with the device. In recent tutorials, we talked about how to work with different autofocus modes and focus points. This knowledge will help you in practice. It will also be useful to read an article on how a novice photographer can evaluate and improve the quality of their own work.

Autofocus can fail when working in low light, and when shooting complex, diverse shots (the camera will not know what to focus on). Such focusing shortcomings can be avoided by simply setting the device according to the shooting conditions. For example, choosing the AF-C constant focus mode and 3D subject tracking when shooting sports will allow you to get much more sharp shots than working with single focus. But there are focus errors that occur systematically, regardless of the shooting conditions.

Back and front focus

In SLR cameras, the phase type of autofocus is the main one. It is with him that you are dealing, working through the viewfinder of the camera. Phase focusing occurs using a separate sensor installed in the camera. As you can see, this is a complex system, and sometimes it can work inconsistently.

The consequence of this will be systematic autofocus errors, called back- and front-focus. In the case of back focus, the camera constantly focuses not on the subject being shot, but behind it. In the case of front focus, on the contrary, the camera constantly focuses in front of the subject. Please note that the presence of back- and front-focus can only be said when the camera makes a mistake with focusing every time in the same direction. If one frame is sharp and the other is not, then the problem should be looked for elsewhere.

Back focus: the focus was made on the face of the girl, and the sharpness ended up behind her, on the fence.

The problem of back- and front-focus is especially terrible when working with high-aperture portrait optics. There, the depth of field will be very small, therefore, any, even minor focusing errors will be very noticeable in the photo. For example, the sharpness in the frame will not be in front of the model, but on the ears.

On the other hand, if you are a happy owner of a whale lens or universal zooms that do not shine with high aperture, you can sleep peacefully. After all, even if your camera has back or front focus, you most likely will not notice it, because focusing errors will be compensated by a large depth of field.

Contrast autofocus

In a SLR camera, in addition to phase focusing, there is another type of autofocus - contrast. You activate it by turning on the Live View mode and sighting the picture through the screen of the device. With contrast autofocus, there can be no back and front focus, since it does not require separate sensors for its operation, focusing passes directly on the matrix. Thus, if phase focusing regularly "smears", try switching to Live View mode and working with contrast autofocus. It works a little slower, but gives more accurate results.

Checking Focus Accuracy

How to check the camera for back and front focus? An accurate conclusion about the presence or absence of these shortcomings can only be given by an authorized service center of the manufacturer of photographic equipment. However, the photographer can make for himself preliminary assessment focus accuracy.

We propose a simple algorithm for such verification.

First, let's prepare the camera.

1. Insert the battery and memory card into the camera. Turn on the camera.

2. Check if autofocus is enabled.

On entry-level models (such as the Nikon D3300 and Nikon D5500), autofocus is enabled by a switch on the lens. It should be in position A.

On advanced cameras, there is a switch on both the lens and the camera. The letter M stands for manual (Manual) focusing. The abbreviation A (Auto) or AF (Auto Focus) stands for auto focus. Both switches must be in the appropriate position to enable auto focus.

3. Press the Menu button, in the "Image quality" item, select "JPEG High Quality". If you know how to work with RAW, you can use this format.

4. Turn on A (Aperture Priority) mode. If you know how to work with manual mode M, you can use it. Open the camera aperture to the maximum value. Everything is simple here: what less number, indicating the diaphragm, the more it is open. In the case of a kit lens, you will most likely have to deal with apertures around F5.6.

5. Set the minimum ISO value. This is usually ISO 100 or 200. This will ensure that test shots are clean and free of digital noise.

6. Now - the most important thing! Let's select the focus mode on one point. It may be called "Single-point AF" in the camera menu.

On entry-level cameras (Nikon D3300, Nikon D5500), autofocus area modes are selected through the menu called by the i button. In the corresponding paragraph, you just need to choose the best option.

On advanced Nikon cameras (starting with the Nikon D7200), autofocus area modes are selected as follows: hold down the button combined with the AF / M switch and turn the front control wheel. In the information display, you will see how the focus area modes change.

7. The point is small - download and print a special target on any printer to check the accuracy of focusing.

There are targets different kind, but the proposed option is perhaps the most popular. In principle, you can check the focus, say, using a regular ruler (how it will become clear later), but it is much more convenient to do this on a target.

Checking autofocus

So, the camera is set up, the test target is printed. It's time to act!

• The camera is best mounted on a tripod.. Without a tripod, such a check will be extremely inaccurate and indicative.
• Provide adequate lighting for shooting. It is best to shoot by the window during the day. You can use a flash (both built-in and external).
• Place the target on a flat surface, and position the camera at an angle of 45 degrees to it at such a distance that the target occupies a significant area of ​​the frame.
• Choose the center AF point. Focus exactly on the target - on the inscription Focus Here (Focus here). A thick black line with this inscription should be located in your frame strictly perpendicular to the optical axis of the lens.

• Take a few shots. Do not use continuous shooting, focus again after each frame. Remember that after focusing, in no case should you move the camera, change the shooting distance. If you are using a zoom lens, test it at different focal lengths. I note that it is most convenient to conduct testing from a focal length of around 50 mm, and you can start with it.
• View received footage. To see them better, do it not on the camera screen, but on the computer monitor. If you see a systematic focus error on all frames, then most likely you have detected back or front focus. It's not worth worrying about this. This is easily fixed in the service center. And owners of advanced cameras (starting with the Nikon D7200) can adjust the focus directly from the camera menu

Precise autofocus performance. Back- and front-focus are absent.

Front Focus: Sharpness was closer than expected.

Fine tuning autofocus

Advanced cameras (starting with the Nikon D7200) have an autofocus fine-tuning feature that will help you get rid of problems with back and front focus, fine-tune the focus system. The convenience of the function is also in the fact that the device remembers the settings separately for each specific lens. Let's say a bug shows up with one of your lenses. You can make adjustments specifically for him, and they will not affect the work with other lenses. When you attach a lens to the camera, it will automatically apply the appropriate corrections for it. Please note that autofocus fine-tuning will only work when focusing through the camera's viewfinder (with phase focusing). When working through the Live View screen, it is not activated, and there will be no need for it, because in this case a contrast type of autofocus is used, which eliminates problems with back and front focus.

Let's see how the autofocus fine-tuning feature works.

Find the menu item " Fine tuning AF".

Autofocus Fine Tuning Menu in Nikon D810

The first item on this menu, as the name suggests, allows you to enable or disable this feature.

The default menu item allows you to enter the AF fine adjustment value to be applied when no separate adjustment has been created for the lens attached to the camera. It makes sense to make such a setting if the device systematically makes the same mistake with focusing with all lenses.

The last item - "Display saved values" - allows you to see all the corrections stored on the camera for various lenses. You can make an autofocus setting for each lens you have, and it will be saved on the camera. Through this menu you can see all the adjustments you have made. In the same paragraph, you can delete unnecessary settings. It is possible to enter your own ID (from 00 to 99) for each lens. This is useful if, for example, you are using two identical lenses and you have made an autofocus setting for each of them. Such an identifier will help you distinguish them from each other in this menu.

The most important menu item is "Saved value". It shows which fine tuning value is currently applied and gives you the option to change it. Once in this menu item, you can fine-tune the operation of AF with a specific lens (installed on the device at the moment).

Fine tuning autofocus

To make the necessary adjustments, you first need to take and examine test shots (as described above). If on the test frames the focus is behind the object, you need to make a negative correction, and if in front of the object - a positive one.

The difficulty lies in determining the desired amount of adjustment. You can find the optimal value using test frames. After making the approximate settings, just take a series of test shots and check if the lens is now exactly in focus. If not, make appropriate corrections.