The phase focusing system of modern digital-mirror cameras is built on special phase sensors that receive an image using additional camera mirror, analyze the data and give commands to the lens to focus in one direction or another.
В JVI special areas are visible on which the focusing is performed. These areas are just a visual representation of the focus sensors. In fact, these areas (points, or zones) of focusing on the focusing module are represented in a completely different way: they consist of vertical and horizontal stripes, as well as the so-called “cross-shaped sensors”. Vertical and horizontal areas are also called linear. Vertical bars (which may appear in JVI like vertical rectangles) are sensitive to the horizontal lines of the frame and insensitive to vertical. Horizontal stripes (which can be displayed in JVI like horizontal rectangles) are sensitive to vertical lines and insensitive to horizontal ones. Cross-shaped focus points (which can be displayed in JVI in the form of squares) were created just in order to be able to focus on anything and not worry about the orientation of the sensor relative to the subject. It is also worth noting that the focus areas can be significantly larger than their visual representation in JVI :)
Canon cameras use multiple focus modules, over time more advanced modules are being used in more 'simple' cameras, and more and more sophisticated focusing systems are being developed for flagship cameras.
In some models, cross-shaped focusing points consist of two components (2 'stripes') - vertical and horizontal, usually called precision cross points (high-precision sensor). Each has different lens aperture requirements. For example, the Canon EOS-1D Mark III camera has 19 cross-shaped focusing points of increased accuracy, but there is only one caveat - for lenses with a maximum relative aperture smaller than 1: 2.8, the horizontal component of such points does not work, and the cross-shaped points themselves turn into Normal vertical-oriented linear focus points (except center).
Please note that this refers to the maximum value of the relative aperture (aperture value F), and not the aperture value at which the shooting will be performed. Focusing is always carried out with the aperture fully open, and it must be taken into account.
If you install a lens with a maximum f-stop of F2.8, then the horizontal components of the cross-shaped dots are turned on and all 19 points work as expected, while having improved accuracy indicators compared to conventional cross-shaped dots. On the one hand, we get increased accuracy with F≤2.8, and on the other, we 'lose' the cross-shaped point with lenses F> 2.8.
There are also camera models in which the cross-shaped point continues to work normally (without increased accuracy) on 'dark' lenses, and when using a high-aperture lens, it simply gains additional accuracy. For instance, Canon 6D with 2.8 lenses
In some models, double cruciform points are used, it can be conventionally said that such points consist of two cruciform points rotated to each other by 45 degrees. Think of it as '+' and 'x' superimposed on each other. This combination dramatically improves focusing performance in difficult conditions.
Table: Phase focusing systems for all Canon EOS cameras. For the sake of this plate, I did the article.
Models | Points / K.t. | Additionally |
D3o, D6o | 3/0 | There are no cross-shaped points, and the available 3 focus points have a vertical orientation. |
300D, 350D, 10D, 1000D | 7/1 | The center point of the conventional cruciform type, works with F≤5.6 |
1100D, 1200D1300D | 9/1 | The center point of the conventional cruciform type, works with F≤5.6 |
20D, 20 Da, 30D, 400D, 450D, 500D, 550D, 600D, 100D, 200D, 250D, 2000D, 4000D | 9/1 | High precision cruciform center point. Enhanced precision sensor works with F≤2.8 lenses, 2.8 lenses |
40D, 50D, 60D,60DA, 650D, 700D | 9/9 | The center cross point has an additional high precision cross-shaped sensor located diagonally to the main one (X-orientation), which works only with F≤2.8 lenses. Thus, the center point is double cruciform. Also, the common center cross-type sensor has a special zig-zag structure, which improves focus by 2 times when 2.8 |
7D, 70D, 750D760D | 19/19 | The center point has an additional high-precision cross-shaped sensor located diagonally (X-orientation), which works only with F≤2.8 lenses. Thus, the center point is double cruciform. Also, the 5 center cross dots (in the vertical row) have a special zig-zag pattern that improves focusing when 2.8 |
7D MarkII | 65/65, -3 EV | All points are cruciform. The center point has an additional high precision cross-shaped sensor that only works with F≤2.8 lenses. If a lens with F> 2.8 is used, the center point is the usual cross. Thus, the center point is double cruciform. All points except the center point are regular cross points with F≤5.6 lenses.
From 5.6 The focusing system supports iTR AF technology - Intelligent Tracking & Recognition AF, which works together with metering sensor and allows you to improve focus on the face, and also allows you to use information about the color distribution in the frame to improve focus. There are features with some lenses. |
6D | 11/1 | High precision cruciform center point. High precision horizontal line sensor works with F≤2.8 lenses, 2.8 lenses |
5D.5D Mark II | 9/1 | High precision cruciform center point. High precision sensor works with F≤2.8 lenses, 2.8 lenses JVI, 2 of which are cruciform, but only at F≤2.8 (at 2.8 |
1Ds, 1Ds Mark II, 1D, 1D MarkII, 1D Mark II N | 45/7 | High precision cruciform center point, high precision sensor works with F≤4 lenses, and 6 more high precision cross type sensors, high precision sensors work with F≤2.8 lenses. If used 4 |
1Ds Mark III, 1D Mark III | 19 (45) / 19 | High precision cruciform center point, high precision sensor works with F≤4 lenses, and 18 more high precision cross type sensors, high precision sensors work with F≤2.8 lenses. There are 26 vertically oriented linear auxiliary points. If 4 |
1D Mark IV | 45/39 | High precision cruciform center point, high precision sensor works with F≤4 lenses, and 38 more high precision cross type sensors, high precision sensors work with F≤2.8 lenses. If 4 |
1D X, 1D C, 5D Mark III, 5Ds, 5Dsr | 61/41
-2 EV |
21 central cross points work with F≤5.6, and 20 lateral cross points work with F≤4 (if F> specified values, the points start working as normal linear ones). 5 center points have additional cross-shaped sensors of increased accuracy and, thus, are double cruciform. Additional cross-type probes of increased accuracy work only with F≤2.8.
From 5.6 1D X, 1D C, 5Ds, 5Dsr use iTR AF - Intelligent Tracking & Recognition AF technology that works together with metering sensor and allows you to improve focus on the face, and also allows you to use information about the color distribution in the frame to improve focus. 5D Mark III lacks this technology because its metering system exposure based on 63-zone sensor. 1D X, 1D C allows spot metering exposure by the selected focus point. |
1D X Mark II, Canon 5D Mark IV | 61/41
-3 EV |
It uses 5 double cross points in the center. 61 points work with F≤8 (including 8 central cruciform points with F≤21). There are 41 cross points in total. 20 lateral cross-shaped points work with 4≤F≤5,6 (if F> specified values, the points start working as normal linear ones). The center point has a sensitivity of -3E.V. There are many features with some lenses. The data on the new focusing module is being updated. |
80D, 90D, 77D, 800D, 850D, 6D Mark II | 45/45 | The center point has a sensitivity of -3E.V. All points are cruciform. The center point has an additional cross-shaped sensor of increased accuracy, located diagonally (X-orientation), which works only with lenses F≤2.8. Thus, the center point is double cruciform. Also, the central cruciform point has a special zigzag structure that improves focus. The X-shaped cross-shaped sensor consists of a double set of sensitive lines.
At 2.8 With F = 8, only 9 center focus points work All points, except the central one, are ordinary cruciform points with lenses F≤5.6. 90D uses metering module / sensor exposure to help focus |
Canon EOS1D X Mark III | 191/155 | Sensitivity from -4 EV. Deep learning technology, head and eye tracking. Work with F / 8. Uses module / metering sensor exposure to help focus |
The instructions for some cameras indicate a list of lenses that do not fall under the general rule of focus points depending on the number F, especially when using teleconverters.
Only 'older' Canon cameras can use one or more center focus points for normal operation with lenses that 5.6.
live view
Also, you can not ignore the focus using Live View, in this focus mode, the main mirror of the camera rises, and focusing is due to the main matrix of the camera.
Model | Live View Focus |
20Da | There is no autofocus in Live View, you need to focus manually. There are 5x and 10x magnification in only the central area of the image. By the way, 5x or 10x magnification is always on, i.e. it is impossible to display the whole picture on the display, with a magnification of 1x. Also, to take a picture, you need to exit this mode, and you cannot change the parameters during viewing. exposure. |
40D, 1D Mark III, 1Ds Mark III | There is no automatic focusing in Live View mode (Quick mode is based on focusing on phase sensors), you need to focus manually. There are 5 and 10-fold increase in the image area. |
450D, 1000D, 1100D, 1200D.1300D 500D, 550D, 600D | Normal 'slow' contrast focusing. Magnification of the selected area is available. |
2000D, 4000D, 7D, 6D, 60D,60DA, 50D, 5D Mark II, 5D Mark III, 1D Mark IV, 1D X, 1D C | Normal 'slow' contrast focusing with face detection. Magnification of the selected area is available. |
650D, 700D, Canon EOS M | Hybrid CMOS AF system is used. Some of the matrix pixels are reserved for the autofocus system by measuring the phase difference, although such focusing works only in the central area of the image and serves only for approximate focusing. Focus adjustment is carried out by usual 'slow' contrast focusing. The full potential of this focusing method is only available with Canon STM lenses. Selected area magnification is available, as well as FlexiZone Single, FlexiZone Multi and Face Priority focus modes. |
100D, Canon EOS M2, Canon EOS M10 | Hybrid CMOS AF II system is used. Some of the matrix pixels are allocated for the autofocus system by measuring the phase difference. The coverage area is 80% (vertical and horizontal), phase focusing in Live View, and is only for rough focusing. Focus adjustment is carried out by usual 'slow' contrast focusing. The full potential of this focusing method is only available with Canon STM lenses. Select area zoom is available, as well as FlexiZone Single, FlexiZone Multi, and Face Priority focusing modes.
|
Canon EOS M3, 760D, 750D | The Hybrid CMOS AF III system is used. Theoretically 4 times faster than Hybrid CMOS AF II technology. Part of the matrix pixels is reserved for the autofocus system by measuring the phase difference. The coverage area is 80% horizontally and 70% vertically. Magnification of a selected area is available, as well as Tracking AF (760D only), FlexiZone Single, FlexiZone Multi, and Face Priority. The system only works properly with lenses with F≤5.6. If F>5.6, normal contrast focusing is enabled. |
70D.7D Mark II | The system uses Dual Pixel CMOS AF. Each pixel on the matrix (80% of the matrix) is divided into two separate photodiodes, for reading the phase difference. Thus, all pixels are similar to phase focus points. Lenses with F≤11 are supported. To fine tune the focus, the contrast method is used. The technology is not trivial, because the detailed explanation is very large. Available enlargement of the selected area, as well as focus modes FlexiZone Single, FlexiZone Multi and the function with priority face. Focusing is fast enough. |
1D X Mark II, Canon 5D Mark IV, 6D Mark II | The system uses Dual Pixel CMOS AF. The technology is the same as that of 70D, 80D, 7D Mark II. Details are being specified. |
Canon EOS M5, M6, M6 Mark II, M50, M50 Mark II
80D, 90D, 77D 800D, 850D, 200D, 250D |
The system uses Dual Pixel CMOS AF. The technology is the same as that of 70D, 7D Mark II, 1D X Mark II. Details are being specified. |
Canon EOS1D X Mark III | The system uses Dual Pixel CMOS AF. Sensitivity -6-18 EV, work with F / 11. Coverage 90% Horizontal and 100% Vertical |
R, RP, RA | Used Dual Pixel CMOS AF system |
R5, R6 | The system uses Dual Pixel CMOS AF II (second generation). Sensitivity from -6.5 or -6 to + 20, available for selection of 1053 focus areas over the entire field of the frame, Deep Learning system |
By the way, when viewing with Live View, all cameras have the ability to use Quick mode, in which the camera exits Live View, focuses using phase focus sensors, and then turns on Live View again. 20Da cameras, 40D, 1D Mark III and 1Ds Mark III really do not have full auto focus in Live View using the camera’s matrix directly.
I would be grateful for the repost and addition of information in the comments :)
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Material prepared Arkady Shapoval.
Now, if we collect such an article by nicknames. And then in nete there is very little information
https://radojuva.com.ua/2012/12/nikon-multicam-all/
Right! He himself saw her with you)
True, anyway, there is little information, but thanks!
You write what is missing or what you would like to see.
Focusing Live View is not enough, the rest is quite detailed.
It is also worth adding that the best quality is provided by the contrast focusing of mirrorless mirrors, shopping mall. front-back focus is impossible there in principle
Great article! ^ _________________ ^
Hurrah! Thank you, great article, Canonists are happy :)))
Oh yes, kenonists rejoice))
Here I have a Canon 6D and one cruciform dot in the center. And now what to sell it and buy 2 times more expensive than 5D mark III?
I would recommend more practice, it usually immediately makes it clear whether you need 6d or something else :)
If you shoot according to the principle: aim the center point at the object, rebuild the frame, shoot - there will be no problems. It is clear business - with static scenes. And for moving objects - how lucky. Usually not very ...
With narrow depth of field when transcoding occurs OH
From experience, in most cases I did not use any points other than the central one at all ...
It all depends on your photo tasks. As already mentioned, in dynamic situations, rescaling is complicated, and the main object does not always have to be in the center of the frame.
Thank you for the article! I recently encountered this phenomenon: animals were photographed in short series, the native flash was activated, after 3-5 minutes of operation, the camera stopped focusing correctly, more precisely, everything was out of focus, took a break, everything worked fine, but then this problem appeared again. Please tell me what this may be connected with. Camera Canon 40d, lens 50 1.8
Hard to tell. I have 40d without problems with 50 1.8 works for a long time. Maybe the flash is the case - there are no problems without it? I can't even think of other options yet ...
Most likely the problem is in the electronics of the fifty kopeck piece. There was also a similar situation with the 50mm 1.8 of the second version, when after 50-100 frames the glass began to “smear” the focus. I took it to the service, they said, the controller firmware flew.
40D in LW has auto focus! But at the same time, the mirror is lowered to focus on the sensors, there is no matrix AF.
This is called a Quick mode in which focusing is carried out by means of a phase focusing sensor, but on the tablet we are talking about a full-fledged Live View, when you can constantly see through the screen. Added a footnote to this article.
In a similar article for Nikonists, there is nothing about the accuracy of AF sensors. I would very much like to read if Nikon has sensors of increased accuracy, in which cameras, with which lenses?
Nikon has a slightly different principle of operation, as such there are no sensors of "increased accuracy" there.
They are all of increased accuracy!
As far as I know, Nikon has ordinary crosses. there are no doubles at all.
This is due to the fact that the best Nikon AF module was developed during the D700 and after that there were endless modifications, but nothing new.
Double crosses require the development of a fundamentally new AF module, algorithms, their connection with the process, etc.
Nikon, in this regard, sits on technology 7 years ago. Alas.
My 30D has constant back focus. I noticed this on a whale lens, but I thought that maybe such a lens. Substituting the same kit, I realized that the problem is in the carcass. I set up a manual lens and tracked the moment the focus confirmation is triggered, which is fed to the defocused image. That is, I see in the viewfinder that the subject is still a bit out of focus, and focus confirmation has already been received. We have to focus on the eye. As far as I know, 30s have an autofocus sensor adjustment screw. Can I adjust the sensor with the home adjustment screw or is it better to contact the service? Although in Lviv unfortunately there are no such services.
It is unlikely that such a screw exists, and if suddenly, then it is unlikely that without certain skill you will be able to adjust the sensor. In Lviv, go to Tsifrovichok. Surely there they will help you http://www.cyfrovychok.ua/page/service.html
And what do you get on the already taken photo? in terms of what is correct, auto focus or viewfinder? although judging by what you write with the viewfinder more precisely, which means that the sensor is knocked down and needs to be returned, or there is a problem with the mirror, it does not sit down to the end, a fraction of a millimeter is enough and the focus will get badly, maybe some rubbish has got. If everything is correct with auto focus, the problem is with the focusing screen, in 30d there are two of them and the one that is closer to the mirror is responsible for the accuracy of the visual focus, the marking is simply applied on the second, the screen can shift either from the impact or from rubbing it. I do not know this by hearsay, I sometimes redo the focusing screens with Doden wedges from old Japanese cameras to the CZK, in the sense of trimming, milling, installing and, if necessary, adjusting.
Do you think that after a year and a half the problem is still relevant?
And I drowned something and did not look at the dates of publication of the comments, the article seemed to be fresh, it looked like the title page, the article was old, but why is it like new ?,
Thank you for poking me with a nose, for the future I will be more attentive.
The article has been updated (as I understand it, the information on Live View has been added), so it is at the top :-)
Yes, that's right, it is, but I got caught with a fool.
It’s a bit confusing; you’re always talking about lenses with a certain aperture value, but don’t talk about the aperture value itself. I have a 6D, Sigma 24-70 f2.8 lens. Based on your table, does it mean that if I set the aperture of this lens, say f8, which has a maximum aperture of 2,8, then I will lose the hypersensitivity of the mid-focus point?
Best regards
Just re-read carefully again:
Thank you for the clarification!
Best regards
Question: If an old Soviet lens is installed on Canon 650D through an adapter ring, M42-EOS with a reprogrammable chip, and the chip is programmed to F2.0, then the camera “thinks” that it has a lens with F <2.8? And it turns out that the central cross-shaped point, which has an additional cross-shaped sensor of increased accuracy, located diagonally to the main one (X-orientation), is working to the maximum? And one more question, the table says: "Also, the usual central cross-shaped sensor has a special zigzag structure, which improves focusing by 2 times, when 2.8
Thank you for the article! Do you happen to know where to find the parameters of phase sensors? Their specifications?
The only article, after a long search on the Internet, that gives an idea of the work of focusing. It’s clear, without a hitch, revealing what the manufacturer is silent about by writing many, many focus points. Thanks to the author for the work and erudition.
Good afternoon, there is a 650d camera and a 50 1,8 lens, when focusing through an OVI, autofocus always smears, and when focusing through the screen, everything is fine. Focus on the center point, the same conditions. I tried 50 1,8 STM in the store, the same problem, except that the focus through the screen is faster. What could be the reason and is this normal?
screen - uses slow, accurate contrast AF
JVI - Fast Phase AF is used
Phase AF is always less accurate than contrast AF and often needs fine tuning.
For this, modern advanced carcasses have the option of fine-tuning the phase AF.
if this option is not available, you need to go to the service with a lens and a carcass for adjustment.
That is, if autofocus misses, then it will only be when focusing through the ovs? I went shopping, with all the lenses like that, but on dark ones it’s certainly less noticeable. I took the camera from my hands, I can’t get it back, I’ll go to the service for adjustment. Thanks for answers. before that Sonya a37 was there wasn’t there, but the lens was only whale.
Not normal. Do you have other glasses, how is autofocus there? Perhaps you need a carcass adjustment in the service center.
Thanks!!! Very useful article!
By the way, why do 5d and 5dm2 have the same autofocus system, but in fact the second brand has fewer problems with autofocus? Apparently, it depends on the processor or are there any other nuances?
The work algorithms are apparently different.
nuances - depending on the firmware.
but in general there are more than enough problems with AF for 5dm2 ...
Here's a question - focusing manually on high-aperture optics: I don't have much vision, I wear glasses. Difficult to get into focus. It can be seen badly - one and the second - apparently the eye is trying to adjust and makes its own correction when focusing in the optical scheme. It turns out the flight! Who has experience in manual focusing - share.
install a new focusing screen with wedges. for 6D, for example, replacing the screen is a matter of 5 minutes.
if it’s difficult on your camera, try live view with a magnification of 5x or 10x.
Friends, I noticed on 6d such a feature that when focusing through live view, the aperture first closes to about f / 5,6 and only then opens completely again, after which the final focus occurs. Moreover, in the daytime under the light of the sun, it hides even stronger at first, everything seems to be clear here, most likely this is the protection of the matrix from the effects of sunlight. But why does the diaphragm hide behind in a dark visit?
Most likely, this is a hard-coded 'behavior algorithm' (roughly speaking, the camera does not know what lighting conditions it is in when it is turned on), or the peculiarities of the diaphragm mechanics.
check if the aperture closes to a larger value, say up to 5.6 when live view if you set say 2.0.
There is also an assumption that due to the greater depth of field when the aperture is closed, it is easier to make a 'rough' aiming, then, when the aperture is open, precise focusing occurs, how do you like this option?
Also an option! By the way, an interesting point, if you set the focus mode to the face, then the diaphragm does not hide.
Premises *
Yes, the diaphragm is fully open. Here is a video if interested https://dropmefiles.com/mZoh8
specifics of the algorithm. There is an opinion that comparing pictures with different apertures, the camera focuses better using contrast AF.
=============
This is Canon's algorithm. Somehow this helps the camera focus in contrast detection mode. Probably grabbing images from different aperture sizes help the camera do comparison to obtain focus.
It turns out that the Canon 6D is not suitable for portrait photography for children? You don't have time to do a reframe, but the focus will smear ... and I noticed that if the background is light, the child is light-skinned with gray eyes, then even the central point does not work very well.
Has anyone come across this?
The camera is suitable, you just need to put more effort into focusing comfortably and accurately.
Maybe a stupid question, but for example? what forces ... the child moves, the focus misses, that is, I understand that you can take 1000 frames and choose 20, everything is fine, the client is satisfied, but a small child is not able to withstand an hour-long shooting and starts being capricious, that is, usually for good portrait shots you first 10-15 minutes, then only lifestyle….
By forces, I mean the development of a certain experience with this camera, when you know in advance how the focus will behave and do the “right” actions to achieve a good result.
Maybe it's not about the focus or I want a lot from the camera, I'll say right away that I'm trying to get to the bottom of the truth, because I bought the camera and I'm trying to understand whether it did not meet my expectations, or the matter is “in my hands”.
Here is an example photo, everything seems to be normal, you can immediately see where the focus is, the child, in principle, is in focus, if you do not zoom in, everything is fine, but if you zoom in, somehow everything is blurry or something, there is no sharpness. Correct me if I'm wrong or tell me what is wrong.
Before that, it was 60D and if you were shooting it was always clear whether you missed or not, everything is clear, if the focus is on the eyes, then all the eyelashes are clear, and not with a slight drag ....
and there is no difference if the shutter speed is 125 or 250, the result is one.
What kind of carcass do you have? And take into account the diffraction, on multi-pixel matrices it starts already from 5,6-6,3 ... plus the mass of the mirror, on some models a micro-shock from the mirror triggering is clearly felt, and this is micro-smear, and the smaller the pixel, the more there are in the matrix , the more tangible this lubrication ...
What lens, FR, aperture, what apparatus?
In the above photo, it seems to me, there is a blur from the movement.
Going to buy a DSLR. Before that, there was a compact, used to sight on the screen. Tell me, can I shoot in Canon7D, Canon750D this way? Will autofocus work? Or just through the viewfinder?
Yes, it will work.
Using only the screen, you lose all the advantages of a SLR camera, maybe it makes sense to look at mirrorless FAs? Large matrix, smaller size, lighter and there is no mirror that you do not need.
Sorry for the repeat, the comment was added incorrectly and it fit in the wrong place.
Question: If an old Soviet lens is installed on Canon 650D through an adapter ring, M42-EOS with a reprogrammable chip, and the chip is programmed to F2.0, then the camera "thinks" that it has a lens with F <2.8? And it turns out that the central cross-shaped point, which has an additional cross-shaped sensor of increased accuracy, located diagonally to the main one (X-orientation), is working to the maximum? And one more question, the table says: "Also, the usual central cross-shaped sensor has a special zigzag structure, which improves focusing by 2 times, when 2.8
Please tell me whether autofocus on the 750D will work with a Canon Zoom Lens EF-S 18-55mm lens (it’s on my 1100D camera). And then I do not understand this at all
100% will be
Thanks for the answer, you really helped!
Canonists and Nikonists are happy, but what should the Olympists do? In general, there is very little information. Maybe because the system camera. Although I am happy with how it removes it, I’ve acquired a different lens.