And so, the lens can miss and the result can be a lot of reasons, both the camera itself and the photographer's mistakes!

Read the article to the end, very useful conclusions at the end!

Reasons for autofocus misses!

First cause - Autofocus Modes! Fotikov has different focusing methods, for example, there is a tracking autofocus! That is, when you choose this focusing method ( Canon - AI FOCUS / AI-SERVO; Nikon and Sony - AF-C / AF-A) as long as your finger is holding the shutter button half-pressed, the camera will track a moving object that falls on your chosen focus point! THOSE. keep an eye on the object, and sometimes when you need not, the camera can refocus - without asking your permission! And the focus will be completely not where you wanted! Therefore, it is better to select the "Once pressed - Once focused!" ( Canon - ONE SHOT; Nikon and Sony - AF S) - when, when you press the shutter button halfway, the camera focuses where you want it and locks autofocus exactly where you need it! She won't refocus anymore!

Autofocus modes. From left to right: Canon, Nikon, Sony.
In tracking autofocus mode, while the shutter button is half-pressed, the camera itself tracks the subject! You can press the shutter button at any time and the subject will be in focus in the photo.

From the first reason it follows second - In the mode "Once pressed - Once focused!" ( Canon - ONE SHOT; Nikon and Sony - AF S) when you have focused and the camera has locked autofocus where you indicated. With a half pressed finger and locked autofocus, you begin to move back / forth, respectively, shifting the focus itself. Those. focused on the human eye and hwe stepped forward, and responsibly focus will go forward in the ear of a man! THIS IS THE MOST COMMON mistake of all novice (and not only) photographers. More often than not, your mistakes are precisely because of this! Or the opposite situation, you focused, and the model stepped back a little, and the focus remained in front of her! You will never notice this in the viewfinder of a DSLR! YES and it is not always noticeable on the screen, therefore CHECK THE SHARPNESS FREQUENTLY - increasing the image on the screen of your camera at the time of shooting, so that you can re-take a picture later!

Do not be lazy to quickly check the sharpness by enlarging the picture. Because you won't see a miss in the general image!
Do not be lazy to quickly check the sharpness by enlarging the picture. Because you won't see a miss in the general image!

The third the reason is AF point selection... If worth AUTO choice, the camera itself will determine exactly where to focus, by itself choosing the desired focus point. The problem is, the camera doesn't know what exactly you are shooting! Her logic is simple - FOCUSING ON WHAT IS CLOSER AND HIGHER CONTRAST! And if in the foreground you have a car hood with a headlight, and a little further a model, then the headlight will be sharp!

Reasons for autofocus misses! And how does it work at all ?!, image # 3

Therefore, it is better to choose the focus point yourself! For the camera itself does not know, what exactly you need to be sharp in the frame, and cannot distinguish a person from a cactus. This is especially true for SLR cameras! But mirrorless cameras CAN, as well as in your phone, they have auto face detection! That is, having seen a face, the camera will focus on it! But if there are many faces, the camera will not know which face you need (Although in SONY cameras you can register the face of your model and the camera will only react to this face!) But still, it's better to choose the focus point yourself!

By choosing the focus point yourself, you can be sure that the sharpness will be right there!
The Sony camera detected the face and focused on it! The question is, is this person what you need !?
The Sony camera detected the face and focused on it! The question is, is this person what you need !?
It's scary to imagine what will happen when the cameras get even smarter!)
It's scary to imagine what will happen when the cameras get even smarter!)

And here we come to the focus points themselves and this fourth reason! If your SLR camera costs less than 60-80 thousand rubles. The focus points are not all the same there. As a rule, the most accurate and sensitive is center point. We will not go into details, the important thing is that it has a cruciform shape and works on any diaphragmx and clings to any lines, both vertical and horizontal, and the rest of the points do not! Therefore, we work like this - directing center point focusing on the subject, press the shutter button to the middle, (to keep the focus on the object) and then without releasing your finger from the shutter button, we position the frame as we need it (placing the object anywhere in the frame) and only after that we press the shutter button to the end and get the frame!

In most entry-level cameras, only the center point catches focus well and unmistakably, others are often mistaken!
In most entry-level cameras, only the center point catches focus well and unmistakably, others are often mistaken!

Remember, autofocus needs contrasting detail to focus! He will not be able to do this on a clean white wall for example! If you photograph a person - always focus on your model's eye - it is there that the most contrasting point! And for example, sony cameras even have such a function, the camera follows the model's eyes! And even in video mode !!!!

And so, the problem of different focus points does not apply to mirrorless cameras, all focus points are the same, and everything works well. This is due to the fact that the focus points of the mirrorless are located on the sensor itself, that is, some pixels partially fulfill the role "Phase focus sensors". What does this mean? Roughly speaking, the autofocus sensor for mirrorless cameras is itself matrix!

But for DSLRs, the autofocus system is a separate module that is located under the mirror below. And for it to work, the mirror must be lowered, at this time you see in the viewfinder the reflection of the picture from lens from this mirror. And count the focusing points - separate micro sensors stuck tightly in this module, and they, as we found out above, are not all the same!

As you can see in the picture, while the mirror is lowered, the light is reflected on the autofocus module and it works! And he works stop the point that we have chosen!
As you can see in the picture, while the mirror is lowered, the light is reflected on the autofocus module and it works! And he works stop the point that we have chosen!
This is what happens when you press the shutter button halfway down and the autofocus module starts working.
This is what happens when you press the shutter button halfway down and the autofocus module starts working.

So the types of autofocus are different and this fifth reason! And not all of them work well! The types of autofocus are - contrast, phase, laser, ultrasonic, etc. All of these methods are widely used in modern smartphones. But in cameras, two are mainly used - contrast and phase!

The contrast method appeared a long time ago (1981), but it began to be massively used only in the digital era, and was used in digital soap dishes and the first more or less smartphones like Iphone 4! It works like this - The camera takes a picture moves lens, takes a picture again, if the picture turned out more contrasting, again moves lens if even more contrasting, still moves lens if contrast got worsethen returns the lens back a little and stops the search - READY! everything is focused! Read for a LONG time? So it focuses for a very long time! The method is the simplest and cheapest, but it requires a lot of calculations, so the speed of such focusing is ooooooooooooooooooooooooooooooooooooooooooooooooooooooo, so the first mirrorless ones didn’t focus very quickly! Not yet invented a phase method of focusing on the matrix!

The lens moves, and the sensor takes a bunch of pictures and analyzes them, and when it finds the most contrasting picture, you're done -focusing succeeded! "Data-baseurl =" "/>
focus successful! "]"> The lens moves, and the sensor takes a bunch of pictures and analyzes them, and when it finds the most contrasting picture, everything is ready - focusing failed!

In contrast to the contrast method - PHASE very fast! It works like this. Light from different angles of the lens, through special. The prism will hit the special sensors that are nearby, the lens moves and the images from different angles are placed in different ways, and as soon as the picture coincides on both sensors, it means we are focused! This method is very fast and all DSLRs use it!

In the first case, I focused too close, in the second - I hit it right, in the third case I focused far, and in the fourth - sooo far!
In the first case, I focused too close, in the second - I hit it right, in the third case I focused far, and in the fourth - sooo far!

So that's why when you turn on Live View ( focusing on the screen, as in video mode) in her DSLR, it starts to slow down wildly and focuses very slowly! After all, the mirror is raised and the phase sensors no longer work! And the SLR switches to the matrix, and there only slow - contrast focusing method!

Why then don't mirrorless cameras slow down, but focus just as quickly like DSLRs and do it on the screen?! Everything is very simple with mirrorless cameras matrix - this is the focusing module, the phase sensors are located on the matrix along with the pixels, and they work as fast as the module that is in the DSLRs under the mirror!

21st century, the autofocus module is in the sensor itself. Your phone, for example Iphone 6/7/8 / X, has the same autofocus system)
21st century, the autofocus module is in the sensor itself. Your phone, for example Iphone 6/7/8 / X, has the same autofocus system)

I must say, not all DSLRs are hopeless, for example, in some DSLRs Canon the system is used DUAL Pixel for example Canon 80D or 5D mark IV and this is an analogue of phase focusing, and everything focuses very quickly on the screen! But then the question is - why is there a mirror and why are they so heavy and healthy! ??

In general - while you buy these healthy DSLRs, clumsy industry mastodons Canon and Nikon will rivet these outdated healthy DSLRs and will not develop the industry! After all, why waste money and time on development, you already buy a healthy black box to look through the periscope like 110 (one hundred and ten) years ago !!!

Then why do we need so many focusing points if we always use one?

And then what is it for at all auto focus point selection? Basically, it is needed for tracking autofocus, where a moving object quickly changes its position in your frame, for example, a running athlete or a racing car, in general, where it is difficult to quickly select a focus point yourself.

The athlete quickly moves in the viewfinder - it is difficult to select a point manually manually!
The athlete quickly moves in the viewfinder - it is difficult to select a point manually manually!

But this function works well only in expensive cameras like Nikon D7200 or Canon 5D mark IV. And also in mirrorless cameras such as Sony A6300. In the entry-level cameras, budget and mid-budget (up to 60 thousand rubles), it is there for show and works extremely poorly!

And finally - sixth reason! This is the front / back focus of your lens! Only SLR cameras have this problem, there is no mirrorless! This is a problem with the phase detection autofocus module. Motor impulses lens do not coincide with the frequencies of the autofocus module and because of this, the motor stops either earlier or later than necessary, and as a result, autofocus jumps or does not reach the target. As a result, by focusing on the eye, you will get either on the model's ear or on the tip of the nose!

In the first case, our focus ran back, and in the second, it did not reach the target! And the middle figure we were aiming at was not very sharp!
In the first case, our focus ran back, and in the second, it did not reach the target! And the middle figure we were aiming at was not very sharp!

And this is completely does not meanwhat is your camera or lens NOT FIXED! It's just that their impulses do not coincide, you can take them to the service for adjustment, but this often ends up with the other lenses beginning to smear. Therefore, it follows immediately when choosing lens, it doesn't matter NEW or BU - always check your DSLR with a specific lens for mistakes! After all, if you find this at home, they will not change the lens for you, firstly it is a technically complex product, and secondly it is completely working, and this does not meanthat with other cameras it will miss!

How to check the lens - the method is described at the link below!

But with mirrorless cameras, you can not be afraid of this, this does not happen there, you can safely order lenses even on the Internet, there will be no misses!

Let's summarize briefly!

  1. If you have an inexpensive camera (up to 60 thousand rubles) then DO NOT USE follower autofocus!
  2. Don't move back / forth when focused on the subject!
  3. Disconnect automatic point selection focus, choose the desired point yourself!
  4. If you have an inexpensive camera (up to 60 thousand rubles), use center point only focusing, as described above!
  5. If you DSLR do not use during focusing by Live view (on the screen), the only exceptions are mirrorless cameras and some Canon models with Dual Pixel.
  6. Required check out your lens on front / back focus!

Article author - Photographer Stanislav Ivanitsky
Stanislav is not only professionally engaged in photography, but also publishes useful videos on your YouTube channel

8 comments on “Causes of autofocus misses! And how does it even work?!”
  1. I bought myself a Sony A7 MII. I work in M ​​mode. Autofocus is on, I take a portrait shot against the background of the building. I select the focus area (face). That's it, the camera saw the face, the green squares on the face lit up (as I understand this is the analysis), the face is in a frame, I'm photographing. I enlarge the photo and see that the face is blurred. Yes, in the general frame it seems to be in focus, but when you zoom in, you can see that it is not clear.
    In the same conditions, I turn on manual focus and get a clear face. What is it? A whale lens? Or am I doing something wrong?
    Lens 28-70.
    And of course, the same is true with tracking autofocus.

    1. Hi. Apparently, by the standards of the camera program, the sharpness is within the permissible range. Try a different lens or the same kit lens at all focal lengths and apertures. Compare the results.

  2. I have the same problem on sony alpha p2. the same as described above. and this can happen 7-8 frames in a row! on two lenses. for some reason he thinks that the bushes behind the model are better suited for sharpness than the face and body. even if you choose the focus on the face-eyes. lens 85mm and 50. that's what it is ?? carry it for repair?

    1. My Nikon Z7 mirrorless camera just works great with Canon TVs (via an adapter). But not buggy. With a Canon 200mm f/2.8 telephoto lens, the focus point cannot be moved left and right from the center line. Otherwise, the percentage of successful focusing decreases from 100 to 0. With the Canon 135mm f / 2.8, this glitch does not exist, but another one often appears: In time priority mode, it often drives the aperture to F22 for no reason and hangs helps off-on.
      Also pay attention to the size of the focus area. On a mirrorless camera, it should be set more, otherwise if a contrasting object does not fall into it, it may miss.

  3. In theory, everything is written correctly, but ... "It was exactly on paper." For a reason completely incomprehensible to me, the focusing of DSLRs depends not only on the carcass, but also on the lens. And you can't get away with explanations about front / back focus. With some lenses (eg Nikon 300mm f / 4 PF ED VR) all serviceable carcasses work perfectly, including the cheapest ones. And on the Nikon D5200-5300, the percentage of clear frames will be very high. With others - from those that I dealt with, Nikon 180mm f / 2.8 V3 and Tamron 70-200 F2.8 A0001 (maybe I confuse the name of the version, in short, the very first one) the percentage of soap frames is at best 90. And so it is and on very expensive carcasses (tried on Nikon D600 and D800). True, if you shoot exclusively stationary objects, then the percentage of clear ones will be noticeably higher. And it is completely incomprehensible why with one glass, when the shutter is pressed to half-stop, the carcass is sensitive to a change in the distance to the object, while with the other it stubbornly refuses to do so. Those. does not do it slowly, but does not do it at all. As a result, if you want, say, to photograph a walking person on a Nikon 180mm f / 2.8, you will have to focus on a foreign object after each shot, and then refocus again. Otherwise, all frames except the first one can be safely sent to the trash. Although it would seem that the mirror is the same and the focusing unit is the same.

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