The new autofocus systems that are found in Canon’s 5Dmk3 and 1DX are the best that the company has yet offered.  Both cameras offer accurate, stable and fast autofocus that is state of the art.  Both cameras share the same AF sensor, with its 61 point layout.  In the 5Dmk3, AF is driven by the camera’s Digic 5+ processor, as well as a second, unspecified AF processor.  Actual autofocus performance is very, very good, (comparable to the Canon 1Dmk4).  In the 1DX,  a pair of Digic 5+ processors assisted by a Digic 4, combine the AF function with a more advanced metering system, to deliver AF performance that has to be experienced to be believed, it is that fast and accurate.

Aside from any differences in how fast the AF functions, setting up the AF between the two cameras is fairly similar.  Where I have found performance differences, I have described settings for each camera separately.  Most of the AF menu options and layout are identical.



Carmine bee-eaters – Canon 5Dmk3, Canon EF 300f2.8 IS lens. Shutter speed 1/3200sec at f/8.0, Iso 800

There is also a tremendous amount of AF fine-tuning available to 5Dmk3 and 1DX users, more so than ever before.  Importantly, Canon have worked hard on the new menu systems that help configure the workings and customizing of the new AF system.  Some of the fine-tuning options that are found on the 5Dmk3 and 1DX were available in prior high-end Canon’s dslr’s like the 1Dmk4 and the 7D, but finding and understanding the settings was not always intuitive.

With the 5Dmk3 and the 1DX, Canon have made it easier for users to take full advantage of all the settings.  Despite these efforts at simplification, the AF system remains fairly complex, and I wrote this guide with the aim of making it easier for wildlife photographers especially, to better understand the available options and what they mean.  To this end, the text is focused on those parameters controlled by the AF Configuration Tool, as well as the Ai Servo priority settings.  Most of the content in this post is relevant for Ai Servo focus operation rather than One Shot focus, and for photography of subjects that may be moving.

Grant Atkinson Canon 5D3 autofocus menu

The new dedicated AF menu on the 5Dmk3

With the 5Dmk3 and the 1DX, Canon have grouped several of the most important autofocus settings together.  This new, dedicated AF menu is colour-coded a purple colour, and located second along the row of menu items, giving some idea of how important Canon consider autofocus.

The very first menu tab, AF1, brings up the AF configuration tool.   With this, there are three parameters that can be adjusted to optimize just how the AF works.  Two of these parameters are different or new, compared to those in the 1Dmk4 and 7D.  Canon have taken the parameters, and created six different combinations of settings, each suited to a different action photography requirement, and named them, Case 1 to Case 6.

The first one, Case 1 (Versatile multi-purpose setting) will work very well for you in most situations.  If you a photographer who really does not want to experiment with the autofocus and are happy with how it performs out of the box, leaving it on Case 1 is a good option.

If you are wondering why I am not describing each Case in detail here, it is because they are intended for sport photography scenarios, and I found it quite confusing to try and decide exactly how a particular Case might match up to my AF needs, which are for wildlife.  It is possible to go into a Case and modify any or all of the parameters, but I still found this time consuming and more tedious than it ought to be.

Instead, I went to the My Menu option, which is colour-coded green and located at the far right end of the camera’s main menu tab.  The ‘My Menu” tab allows you to choose whichever items you consider important to you, and group them under a single menu.

Grant Atkinson Canon 5d3 menu

Selecting ‘Register to My Menu’ allows you to choose which menu items you want to group together yourself.

By choosing My Menu Settings, and then Register to My Menu, I was able to scroll down the complete list of menu items.  I then selected the three AF parameters, Tracking sensitivity, Acced./decel tracking, and AF pt auto switching.

Grant Atkinson 5Dmk3 menu screen

Scroll down the list of all menu items until you find those three that are controlled by the AF Configuration tool and select them.

I now have these parameters neatly arranged one below the other in My Menu.  My camera defaults to the My Menu tab when I switch it on, so no more digging my way through Case 1 to 6.  Importantly, this change also allows me to concentrate on using these settings for my shooting situations, without having to modify the presets with their sport photography descriptions.  And it means that by thinking about what I am doing each time I change a parameter, I am now hopefully making considered choices when fine-tuning my AF, rather than taking a guess with a preset.

Grant Atkinson Canon 5Dmk3 rear lcd

This is the My Menu options chosen for my own 5Dmk3. Tracking sensitivity, Accel/decel. tracking and AF pt auto switching are grouped together.

It helps to describe what each of the three AF parameters do:

Tracking sensivity – This setting controls how long the camera will ‘wait’ before refocusing, when a new subject/object moves between the camera and the original subject.  An example of this is when you are tracking a bird, and the bird passes behind a branch, momentarily.  With this setting on Responsive +2, it is more likely that the AF will quickly lock onto the branch.  If this setting is on Locked-On -2, it is likely that the camera will hold the focus for longer, without attempting to re-focus for long enough that the bird can once again be located once the obstruction has passed by and out of the line of sight.  Another example of just when this setting will help is when you are tracking a moving subject with an active AF point on the subject, and you accidentally move the camera so that the active AF point drops off of the subject.  With Tracking sensitivity set to -1 or -2, there will be more time available to you to re-locate the subject, without the lens having focused on the background.  Canon do mention that with Tracking sensitivy set to the Locked-On side of the slider, that it may take the AF a little longer to re-aquire focus if focus is lost.  Canon also state that initial AF acquisition is not affected by setting Tracking sensitivity to Locked-On (-1 or -2).  The key to avoid paying any possible speed penalty with re-aquisition is to try hard to keep the camera/lens focused while tracking the moving subject.  Tracking sensitivity  is probably the most important of the three parameters described here in that it can make a noticeable difference to how stable AF tracking is.  I have found this most noticeable, and most necessary when shooting very long telephoto lenses, from 500mm upwards.  When using such long lenses, and tracking a subject that is nearby, moving the AF point off of the subject can result in the AF locking onto the background.  When this happens, with some longer lenses it is possible for the image in the viewfinder to become so blurred that it becomes difficult or almost impossible to actually see where the subject is through the viewfinder.  This can make using such lenses very frustrating.  Tracking sensitivity can be very valuable in allowing the user more time to get the AF point back on the target, before it refocuses on the background or foreground.

With shorter lenses, the amount of defocus is not so great that you cannot still see the subject in the viewfinder, and then you can just aim an AF point in the general direction, and press the shutter button/AF-On button to make the lens search and lock on, so Tracking sensitivity is still very useful, just not quite as critical.

In my own use, I tend to set the tracking sensitivity to the (0) setting when using lenses up to about 300mm, or to (-1) if I am shooting against a busy, background that might be similar in tone and contrast to my subject.

If I am using lenses longer than 300mm, then I am more likely to set the tracking sensitivity to (-1), and on very long lenses over 600mm, may even use (-2) on occasion.

I am also finding other shooting scenarios, such as when faced with a subject moving rapidly, and directly toward the camera, that changing the tracking sensitivity to (0), or (+1) or even (+2) may deliver better results than the (0) or negative settings.  This may be more true with the 5Dmk3 than the 1dX.  Such head-on approaches are not encountered that often with the wild subject matter that I shoot, but as my time in the field with both of these cameras builds up, so I am able to continuously share findings.  There are also some valuable experiences shared by other 5dmk3 and 1DX users in the comments section that follows on at the end of this post.

Accelerate/Decelerate tracking – This setting allows the AF to be optimized to capture fast-moving subjects that might suddenly stop, or move in a random direction, or rapidly speed up or slow down.  The 0 setting for this parameter is suited for tracking subjects that move at a steady speed.  Most of the subjects that I shoot accelerate or decelerate whilst i am tracking them.  Also, if I have a subject coming towards me, even if that subject is staying at a steady speed, I have to allow for the relative increase in speed the closer to me that subject gets.  Think of trying to track a bird flying towards and right by you…your panning motion has to speed up dramatically as the subject gets closer to you and actually passes by.  As I like to try and shoot fast moving subjects whenever possible, I have started leaving this setting on (+1) with good results.  According to Canon, setting it to (+2) will make it very responsive but also a bit less stable.  At the time of writing I have not found need yet of using this setting on (+2).

AF Point Auto Switching – If you are an action photographer that prefers to always use the camera in Single AF point mode, or Single Spot AF, then you can disregard this parameter.  It’s function only applies when shooting with those AF mode options that utilize more than one AF point.

On the 5Dmk3 and 1DX, these are : AF Point Expansion (selected plus 4 surrounding), AF Point Expansion (selected plus 8 surrounding), AF Zone, and 61-Point Automatic Selection Point AF.

AF Point auto switching controls how rapidly the AF will switch to a new AF point whenever the initial or primary AF point (again, only when there is more than one AF point active) leaves the subject.  It will rapidly switch to surrounding AF points to continue to follow the subject.

The (+1 and +2) settings are used when shooting subjects with faster, erratic movement in any direction,whilst the (0) setting provides a more stable switching of AF points.  To date, I have not felt the need to change this setting from (0) on either the 5D3 or 1DX.  I tend to shoot mostly with a single manually selected AF point, but I do sometimes use the AF Zone grouping on both cameras, and have found the point switching to be fast enough to date on the (0) setting.  The action of this parameter is easy enough to understand.

Grant Atkinson Canon 5Dmk3 AF menu

The AF2 menu tab on the Canon 5Dmk3.

The next tab on the AF menu is called AF2:Ai Servo.  The parameters here control how much time is allowed for focus to take place, before a frame is taken. It is possible to select between  speed (with limited time allowed for focus) or focus priority (with more time given for focusing to take place).  This preference can be set separately  for the first image in a burst and then set again for the rest of the frames in the burst.  One might wonder why not just prioritize more time for focus to take place, as that should result in a higher percentage of in-focus images.  However, there is a trade-off  involved here, and more time for focus can slow down the frame rate and response.  My shooting requirements may not be the same as yours, but for the wildlife photography that I do, my preference is for a mix of speed and focus priority.

The settings are made after selecting the menu item Ai Servo 1st image priority as shown in the image above.

Grant Atkinson Canon 5Dmk3 screen

The Focus priority setting in the Ai Servo focus/release priority setting screen

5Dmk3 and 1DX

The control in this screen applies to the first shot in an Ai Servo burst.  The slider determines how much time is permitted for focus to take place before the image is taken.  If the slider is set to the far right, as in this  image, to Focus, then the maximum amount of time is allowed for focusing to take place.  This can lead to a hesitation before the shutter actually trips, and almost makes the shutter button feel ‘spongy’, especially on the 5Dmk3.  When this slider is set to the Focus position as in the image above, the camera is programmed to not allow the image to be taken until the camera thinks it is in-focus.  This is what can lead to the slight hesitation, especially if the subject is a difficult one for the AF to pick up or track.

Grant Atkinson Canon 5d lcd

Ai Servo option set to Release, for quickest response on the Canon 5Dmk3

5Dmk3 and 1DX

Staying with setting up for the first image in a burst, and Ai Servo 1st image priority, I set both the 1DX and the 5Dmk3 to the Release priority option as displayed above.  Often, as a wildlife photographer I am presented with fast-moving subjects that appear unexpectedly.  I like to have my cameras to be instantly responsive, as sometimes I may only get off one or two shots.  I am happy with the percentage of in-focus images that I am getting with both the 5Dm3 and the 1DX, with Ai Servo 1st image priority set to Release.  This means that I can get that all-important first shot off as quickly as I can, with no hesitation or lag.  For those users who don’t need the maximum amount of responsiveness, there is a middle setting on this slider, which means that the camera gives equal priority to focus and other words, a little more time for focus, and not quite as quick a response but I prefer to select the Speed option, as highlighted in the image.

Grant Atkinson Canon 5d3 rear screen Ai servo menu

The Canon 5Dmk3 Ai Servo second image Ai Servo adjustment setting.

5D3 only

Once you have chosen Release/Speed or Focus priority for your first image, the next option in the AF menu is Ai Servo 2nd image priority.  With this parameter the user decides how much time will be utilized for AF to take place before each shot, from the second shot in a burst, and all those that follow in that same burst.  The same choice can be made in the menu as with 1st image priority.  With the 5dmk3, I choose Release for this option.  With those settings, the 5Dmk3 will maintain a continuous shooting speed of 6 frames per second.  If the middle setting, Equal Priority, or the Focus priority setting is chosen, the continuous speed can slow down.  This will usually be experienced when trying to track subjects against similar backgrounds, or in low light.

On the other hand, with the setting on Speed, the 5Dmk3 AF seems to have no difficulty in getting high percentages of focused shots, of fast-moving subjects, at 6 fps.

Grant Atkinson Canon lcd Aid servo menu screen

The intermediate setting is one i use often on the 1DX from the second image in a burst onwards.

 1DX only

Once you have chosen Release/Speed or Focus priority for your first image, the next option in the AF menu is Ai Servo 2nd image priority.  With this parameter the user decides how much time will be utilized for AF to take place before each shot, from the second shot in a burst, and all those that follow in that same burst.  The same choice can be made in the menu as for with 1st image priority.  With the 1DX, I choose the middle setting, Equal priority.  With those settings, the 1DX will still hammer off more-in focus images at a very fast rate, and with a higher percentage of in-focus images than with any other camera I have used.  If the Equal priority setting does slow the frame rate at all, when shooting subjects that are difficult to focus-track, the camera is still faster than any other Canon I have used, on any setting.



In this text, I have described in some detail, the working of the three parameters that influence how AF functions, those being Tracking sensitivity, Accelerate/decelerate tracking and Auto switch AF points and my own choice of settings.  For these three parameters, I find no difference between the 5Dmk3 and the 1DX, and my settings are the same on both cameras.  The 1DX is unique in that it has one option not available on the 5Dmk3, and that is EOS iTR, or ‘intelligent tracking’, where colour and shape recognition input are used to aid focus.  However, as this option is only available when one is using all 61 AF points in fully automatic mode, which I don’t do, so I have left off describing this function any further.

Further to that, the parameters that control how much time is allowed for focus to take place, before each frame is taken, were described, and differences detailed, Ai Servo 1st priority, and Ai Servo 2nd image priority.  For these priority settings, I set the 5dmk3 slightly differently to the 1DX as detailed in the text.

Some of the adjustment parameters under discussion here are similar to those found in the Canon 7D and the 1Dmk4, and even to the 1Dmk3.  Tracking sensitivity on the 5Dmk3 is the same as Ai Servo tracking sensitivity in the 1Dmk4 Custom Function menu, C.Fn3.2.  And the Ai Servo 1st and 2nd image priority settings are also in the 1Dmk4, Custom function III, 3.  The options are not exactly the same as those in the 5Dmk3 and the 1DX, but they are similar.

Lens choices have a big impact on how autofocus works for you.  Canon L-series lenses have motors that drive their AF very rapidly.  Using non-L series lenses, or third party lenses may have an effect on AF performance.  I wrote this text, based on experience that comes from shooting the Canon 5Dmk3 and the 1DX extensively with these lenses:  Canon EF 70-200 f2.8 IS II, Canon EF 70-300L f4-5.6 IS, Canon EF 300 f2.8 IS II and I.

Lenses with shorter focal length will typically focus faster than lenses that have long focal lengths, all other things being equal.  It is also much easier to locate and focus, and re-locate subjects with shorter lenses than with long lenses.

Lenses with large maximum apertures will usually focus faster than those with smaller maximum apertures.  Keep both focal length and maximum aperture in mind when making use of the AF adjustment parameters, and when comparing your own results.


If you are a photographer that likes to target moving subjects,  then both the 5Dmk3 and the 1DX are going to help you get that right, better than ever before.