5D Mk IV: Understanding AF, AI Servo, back button focusing, and tracking - complicated issue

[KarlKrueger]

I hate to admit this but I have been using a 70D and then the 5D IV for quite a number of years but in reading the manuals over and over again I just don't get it. How should I work the 5D IV  to achieve focus on my subject, and have it tracked to keep focus on it? My settings have been keeping AI Servo on, I use the center AF with the surrounding 8 points to support it, and focus with the back button, with the shutter button not doing focus. I try to get my subject on the center AF when I focus but that is not usually easy. Birds in flight are fast so I find this as a joke when in the manual they talk about focusing on a person.  Even jets in an airshow are a cinch compared to my usual subjects.

I have had some flight pictures turn out great. Others are out of focus. Without knowing what is really happening during tracking this becomes a crap shoot on my level of success.

1. When I do the back button focus during AI Servo should I keep the button depressed or can I release it and try to keep the subject in the frame? The only time I can see what AF points are achieving focus is when I use an AF zone. So with my center nine selection I never see if tracking is being maintained. From doing ducks while swimming it looks tracking is not happening.

2.  The manual says the camera should pick the closest object when multiple AF points are selected. This does not happen in my experience. With moving subjects normally the background scene is chosen or if water is involved the high contrast on the water surface is selected. That is why I have resorted to only using the single AF point to focus because the camera sure is not smart enough or am I doing something wrong.

3.  With the center 9 AF points I am using, with the center being the primary, does that mean tracking can only occur among those 9 points? If so that doesn't leave much room for movement of the subject.

4. There is an option to use the entire collection of AF points but set the initial focus on a selectable point. Why don't I see my selected point when I activate this feature - rather useless when I don't have time to locate the exact position of that point on a fast moving target?

It would sure help if the manual was much clearer in describing concepts like this. I feel like I have using trial and error to see what ever works for me.

[Waddizzle]

If you expect every shot you take of BIF to be a keeper, or a near keeper, then your expectations are way too high.  People talk about "keeper rates" all the time, and the keeper rates for BIF are never 100%.  Every shooting scenario is different.  Your location relative to your subjects can dramatically impact your keeper rates.

1) The BBF button is like an ON/OFF switch for the AF system.  When you press it, the camera focuses.  When you release it, the camera stops focusing.  I only use BBF in One Shot AF mode, so I can separate focusing from the shutter.  I think of it as my "bird on a branch, sitting in a tree" mode.  I can lock focus, and then not worry about the camera refocusing when I press the shutter.  I save this mode as a custom shooting mode.  I also use the back button as [AF-OFF] when I am shooting in AI-Servo mode.  I save this mode as a separate custom shooting mode, too.

2) What the manual is saying is true, and you can use that behavior to your advantage by choosing a shooting location with that in mind.  But, the manual may also be describing the default behavior of the camera out of the box.  That is how P shooting mode should work when you select AI-Servo mode.  The camera will have all AF points enabled, and you should see the tracking in the viewfinder.

3) AF tracking and AF focusing are totally separate.  With only the center AF point and its' 8 surrounding AF points enabled, you are doing the tracking of the subject, while the camera is taking care of the focusing on the subject.  Yes, it does not leave much room for error, which is why I use BBF for [AF-OFF], so I can reset the AF system with a quick tap when I lose focus on the subject.  Shooting BIF with just the center 9 AF points takes some skill and lots of practice.  Enable all of the AF points, or use the entire large AF zone in the center, so you can gain practice at tracking BIF.

4) The default behavior of the camera should be to display all of the active AF points.  This allows you to see AF tracking in real time when using AI Servo mode.  There are a number of AF display settings, and some can disable the real time tracking display.  I suggest that you reset the 5D4 back to factory defaults, and try P mode using AI Servo focusing mode and Continuous Drive shooting mode.

Canon has better documentation than the competition.  Canon also offers AF focusing guides in its' Digital Learning Center.  I do not know if there is one specifically for the 5D4.  But there have been AF guides for the 7D2 and the 1Dx bodies.  The AF systems in all of the high end cameras work pretty much the same way.

[ebiggs1]

I noticed the above post tries to explain but...........keep it simple until simple works.

This basic mode does not include BBF or Ai-servo, or any advanced feature. Just keep it simple.  There is a reason this stuff is not on the first page of the manual.  And, you are learning tracking and keeping the subject in the frame. Usually the eye of the subject. This isn't in the manual. Experience is key.

[ebiggs1]

"I feel like I have using trial and error to see what ever works for me."

And, this is exactly why you haven't been as successful as you would like. As noted above, no body gets 100%. Perhaps 50% is a more true number.

This is what you need to do. Just as babies learn to crawl, then walk and finally run, you need to do the same. Also let's start with larger birds and shorter lenses.  Maybe a 300mm f4 for instance. Eventually working up to something like the 150-600mm super zooms.  Larger and slower birds to start, too.

So let's set the Mk IV to One shot, center focus point only (no side helpers).  ISO pretty high at least 800 and 1600 on a Mk IV is good. Av mode and a more open aperture.  Always Raw file format but you can set Average WB if you want.  We'll work that out and other settings in post editing. Try for Sunny days at first. Now go out and shoot.  Shoot a lot. Shoot this way until you do see this resulting in more "keepers" than deleters.

OK, let's move on to more challenging birds. Smaller and faster.

I had a friend, he quite photography because he said he just could not get it.  He wanted to do BIF, too, but his chosen favorite bird was the hummingbird.  Very small and believe me very fast.  Anyway he got nothing worth keeping. Got discouraged and sold all his gear. I told him, boy, did you ever pick one of the hardest birds to start with. Not even knowing your camera well enough to do stills.

Anyway start slow and big. Advance to the more difficult as you become comfortable and its second nature for you. Don't change any thing until this basic stuff works. Learn one thing at a time.

BTW, if you don't have big birds to shot, dogs and cats are usually willing subjects!

[jrhoffman75]

https://www.youtube.com/embed/cWc0O_i65MM

[Waddizzle]

https://www.youtube.com/playlist?list=PLp-znpQge8HyK4n-gp2Jhd_T4zsi2bbJw 

Here is a playlist of tutorial videos on the Canon USA YouTube channel that cover the EOS 5D Mark IV.

[Waddizzle]

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@Waddizzle wrote:

https://www.youtube.com/playlist?list=PLp-znpQge8HyK4n-gp2Jhd_T4zsi2bbJw 

Here is a playlist of tutorial videos on the Canon USA YouTube channel that cover the EOS 5D Mark IV.

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Here is a video from the playlist that will answer your questions.  Pay close attention at around the 4:00 mark. 

https://youtu.be/KY6VHltC-1U 

If you are having trouble tracking subjects using the center AF point plus the 8 surround AF points, I do not see how using just the center AF point and One Shot mode would be of much help to you.  You are wanting to learn AI Servo.

That might be good advice for absolute beginners looking to learn the Creative shooting modes.  But, it really does not address your questions, and your are NOT an absolute beginner.  That advice seems to completely ignore all of your questions.

Use P, Av, or Tv mode.  For action photography, I prefer to use M mode with ISO Auto, which is an approach that has become very popular among professional sports photographers.  Some of my friends.

[amfoto1]

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@KarlKrueger wrote:

I hate to admit this but I have been using a 70D and then the 5D IV for quite a number of years but in reading the manuals over and over again I just don't get it. How should I work the 5D IV  to achieve focus on my subject, and have it tracked to keep focus on it? My settings have been keeping AI Servo on, I use the center AF with the surrounding 8 points to support it, and focus with the back button, with the shutter button not doing focus. I try to get my subject on the center AF when I focus but that is not usually easy. Birds in flight are fast so I find this as a joke when in the manual they talk about focusing on a person.  Even jets in an airshow are a cinch compared to my usual subjects.

I have had some flight pictures turn out great. Others are out of focus. Without knowing what is really happening during tracking this becomes a crap shoot on my level of success....

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Hi Karl,

The truth is that no AF system can deliver 100% in-focus shots every time. There are just too many variables. Keep in mind that it's a "system" involving the camera, the lens AND the user themselves. The first thing you need to accept is that there will always be some times when you miss focus. All you can do is try for the highest percentage of  well focused shots possible.

Canon AF systems are pretty darned good! You mention your camera, but not the lens(es) you're using. USM lenses are Canon's fastest focusing. STM lenses are pretty good too, though not quite as fast. Micro motor lenses are the slowest. There aren't any Canon lenses than are otherwise identical, but have used all three types of focus drive, where we could make the most accurate possible comparisons... But the EF-S 18-135mm IS USM lens is nearly identical to the EF-S 18-135mm IS STM lens, other than their respective focus drive systems, and Canon states the USM is 2X to 4X faster focusing. The USM lens actually uses Canon's latest-and-greatest "Nano USM" , which is both fast like USM and quiet/smooth like STM. (The earlier versions of that lens with micro motor drive use a different optical formula, so can't really be compared.)

Can't really say how third party lenses compare, if those are what you're using.... At least theoretically, Sigma's "HSM" and Tamron's "USD" should perform similar to Canon USM. AFAIK, all Tokina lenses use a micro motor. An example, among my kit of Canon lenses I have a Tamron macro lens that uses a micro motor focus drive. It's simply too slow focusing to use for action photography. It's slow to acquire and can't keep up with and track movement (this is typical of macro lenses in general, though... even with higher performance AF drive they tend to use "long throw" focus design that emphasizes precision over speed). 

Lens aperture is another consideration. Not the aperture you choose to take the shot... but the lens' maximum aperture. The larger that aperture, the more light reaching the AF sensors in the camera to aid with focusing. In fact, many (most? all?) Canon DSLRs have at least one "f/2.8" sensor at the center that's higher performance when f/2.8 or faster lenses are used on the camera. Further, there may be other differences between the AF points... some are higher performance "dual axis" or "cross type", while others may be lower performance "single axis" (some of which are vertically oriented, some horizontal). Study the 61-point AF system of your camera to learn if it has different types.

I can't fault how you've set up your camera (part of the "user" aspect of focus performance)... It sounds similar to how I might set mine up for Birds In Flight. (BIF are a very challenging... fast and erratic... moving subject.) I have to note, I don't use a 5DIV. I currently shoot with a pair of 7D Mark II and an older 5DII (which has a much simpler and more basic AF system... I don't typically use it for action photography... I use it for more sedate stuff like portraits, macro, landscapes).I also used a couple of the original 7D for about five years, which have an AF system very similar to your 70D's.

For example, I know from studying them that all 65 AF points in my 7DII are the dual axis type, while only the very center one is f/2.8 type. The same is true of all 19 AF points in my original 7D. My 5DII, on the other hand, only has a single visible dual axis point at the center. That camera's other 8 visible AF points are a mix of single axis type. (5DII also has 6 "invisible" focus assist points that can be enabled, clustered right around the center AF point... two of those are dual axis... but these only work in AI Servo mode.)

I'm only including that info about my cameras to illustrate what you need to know about your camera's AF system, to get the best out of it.

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...1. When I do the back button focus during AI Servo should I keep the button depressed or can I release it and try to keep the subject in the frame? The only time I can see what AF points are achieving focus is when I use an AF zone. So with my center nine selection I never see if tracking is being maintained. From doing ducks while swimming it looks tracking is not happening....

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I agree with Wadizzle that the AF On button basically serves to start and stop the AF system. I disagree, though, with using it only for One Shot focusing. In fact, one of the top reasons for setting up and using Badck Button Focusing (BBF) is to be able to use AI Servo as your default focus mode, to be ready all the time... at the touch of a button... for BOTH moving and stationary subjects.

One of my "user tricks" to maximizing the percentage of in-focus shots is to use as few AF points as possible. If you think about it, this makes sense. Whenever multiple AF points are enabled, there is a chance that the system will focus somewhere other than where you'd like. Even with a BIF, when multiple AF points are active one of them may focus on the closest wing tip and allow the bird's head and body to go out of focus. If, on the other hand, you were using a single point and keeping that directly on the bird's head, that's where the camera and lens will focus most fo the time. "Tracking" occurs when a single AF point continuously updates focus, as long as you maintain pressure on the AF On button (using BBF and AI Servo).

The problem is, using a single point is a lot more work for you and me! It's up to the photographer to keep that AF point right where they want the camera and lens to focus. And, assuming they're using camera and lenses with fast acting AF, for the large part they'll only have themselves to blame for any missed focus shots. 

Usng BBF with AI Servo to track moving subjects you have to maintain pressure on the button to keep AF working for as long as you want the camera and lens to continue focusing.

In One Shot mode you get "Focus Confirmation". In most Canon a green LED lights up when focus is achieved. It also may flash one or all the AF points red, when focus is achieved. Optionally, the camera might give an audible "beep" (I have this enabled on my cameras, because it alerts me if I have the camera set to One Shot... the incorrect mode to use for moving subjects that I shoot a lot.)

In AI Servo mode, which is what you need to be using when shooting moving subjects, there is no Focus Confirmation. If you think about it, this makes sense. One Shot achieves focus, stops and locks, then gives the confirmation (but if you or the subject or both move, focus is likely to be incorrect, since the AF system has "locked").AI Servo, on the other hand, runs continuously until you stop it. It never stops so there's nothing to confirm. (Some cameras, including my 7DII, have a little indication that AF is operating... "AF" appears in the viewfinder. I don't know if 5DIV have that. My 5DII doesn't. Neither did my original 7D.)

Working without Focus Confirmation is a bit tricky at first. But as you get to know how quickly any given camera and lens combo perform in various situations... learn to trust both it and yourself.... you should become accustomed to not depeneding upon Focus Confirmation.

Be careful.... Don't accidentally set "AI Focus". That's not really a focus mode at all. It's automation where the camera tries to determine for you whether or not the subject is moving, then it will switch to what it deems to be the correct focusing mode. Personally I never use that. When I experimented with it years ago I found it caused some delay and sometimes chose incorrectly... or failed to change modes if a subject stopped or started moving. The similarity of the name with AI Servo makes it easy to choose AI Focus accidentally. (Note: It might be a clue, the most pro-oriented models in the 1D-series don't even have AI Focus... they only have One Shot and AI Servo.)

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...2.  The manual says the camera should pick the closest object when multiple AF points are selected. This does not happen in my experience. With moving subjects normally the background scene is chosen or if water is involved the high contrast on the water surface is selected. That is why I have resorted to only using the single AF point to focus because the camera sure is not smart enough or am I doing something wrong...

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This is correct. When multiple points are selected, the camera may choose to use one other than you'd like... And it will usually choose to focus upon whatever is closest and covered by an active AF point. This is one of the risks of using multiple points.

I try to only use multi-point focusing patterns when subjects are well-separated from possible distractions... when the background is distant or very plain (a blue or overcast sky, for example... or distant mountains, trees etc.). I avoid it when the subject is very close to a busy background or there are a lot of obstructions I'm "shooting past". When using BBF and AI Servo, you can "dodge" obstructions between you and the subject by momentarily lifting off the button, then re-applying it when the subject emerges from behind the obstruction.

There may be menu settings in your camera where you can adjust how quickly the AF system "jumps" to a different object. I know in my 7DII this can be set separately for the first image in a burst and for second & all subjsequent images in the burst. I set this to "slow" with unfamiliar subjects or when I'm out of practice. But I may set it faster with subjects I know what to expect and have good handle on tracking.

There also may be a "priority" setting, where you can tell the camera whether or not to release the shutter if focus hasn't been achieved. I have little use for out-of-focus shots, so I set this as high as possible. (A photojournalist might choose the opposite, if "getting the shot" is critical, regardless of focus.)

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...3.  With the center 9 AF points I am using, with the center being the primary, does that mean tracking can only occur among those 9 points? If so that doesn't leave much room for movement of the subject...

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The basic answer to your question is "yes", focusing can only occur with the AF points you've selected.

I am not certain about the 5DIV, but with my 7DII there are two different "focus patterns" that might be what you describe.

One pattern is "Zone" (two sizes, 9 points would be a "Small Zone" on my cameras). This pattern is very much like a scaled down version of  All Points/Auto. With the Zone pattern selected, you only get to choose the region of the AF array that will be active. You do not get to choose the "starting point". The camera is allowed to automatically choose any of those points it "thinks" it should start focusing with. As noted previously, it will usually choose whatever is closest and under one of those active points. All Points/Auto does the same thing, but with all the AF points in the camera. You might also have a Large Zone option, too... with 15 or more AF points active in the same way.

The other simliar pattern on my cameras is "8-point Expansion". It looks similar, but operates differently. With this pattern you do get to designate the specific AF point you want the camera to use, but have "given it permission" to switch to using any of the eight AF points immediately surrounding it, if you fail to keep the starting point right on the subject. There's less risk of the camera mis-focusing with this, but it's still possible (as it is with any pattern using multiple points).  There is also "4-point Expansion" on my cameras, which only allows the points immediately above, below, right and left of the one I select to take over focusing, if needed.

I occasionally use Small Zone sometimes with fast, erractice subjects like BIF... when they are well separated from the background and obstructions. I wouldn't use it for a duck swimming on a lake.

I more often use the two different Expansion modes, though it's still not a whole lot. These I use with erratic moving subjects on the ground, I'm having trouble tracking with a single point. Usually I will only use 4-point for subjects that stay grounded... but for subjects that might jump or something, I may use 8-point. Choosing between them really depends upon the moving subject's possible directions of travel.

But I don't use either of those multi-point modes anywhere near as much as I use Single Point.... because that puts me most fully in control of exactly where the camera and lens focus, even though it's a lot more work for me! Zone and Expansion focusing are "specialty" patterns I only use in specific circumstances.

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...4. There is an option to use the entire collection of AF points but set the initial focus on a selectable point. Why don't I see my selected point when I activate this feature - rather useless when I don't have time to locate the exact position of that point on a fast moving target?

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You don't get to choose a "starting point" when using All Points/Auto. Think of this as a "point n shoot" mode. It basically leaves all the focusing decisions up to the camera. And since the camera doesn't have your brain, it will choose differently than you'd like a lot of the time. I never use All Points/Auto on . I tried it very briefly (around 20 years ago with EOS-3 film cameras)., but it gives up too much control for my liking.

With many Canon I've used, there was only the option of Single Point/Manual Selection or All Points/Auto Selection. So I only used Single Point, most of the time. Beginning with 7D and even more-so with 7DII, I now have a lot more options... add'l focus patterns, more focus customizing and tweaking options. They are probably similar to your 5DIV's, though I'm sure there are some differences too. But I've spent time trying things and learning... making one change at a time and seeing how it works, reading information about the system, watching some videos, etc. It takes time to learn, because these newest  AFsystems are pretty complex. What works for one situation, might not be ideal in another.

Some other things that might help....

Some modern zooms are "varifocal". This means they don't maintain focus when zoomed to a different focal length ("parfocal" zooms do). It's important when using One Shot to know if you are using a varifocal zoom, because you have to remember to re-focus after making any adjustments to the zoom. With AI Servo, particularly when using BBF, there are no worries. The AF system will instantly correct for any loss of focus from zooming the lens.

Don't shoot wide open when it's not necessary. Stopping your lens down a bit increases depth of field, which can hide minor focus errors (which can and will occur with moving subjects). Of course, you have to balance this against desired background blur or  lighting conditions that might force you to use larger apertures to have the shutter speed/ISO combo you want. But I'd rather add blur to a background in post-processing or use some extra noise reduction, if necessary, than deal with missed focus or too shallow depth of field.

Pre-focus when you can. If you know a subject is going to be coming to a particular point where you want to photograph them, focus there in advance so that you camera and lens are close and don't need to do much to complete the focusing process.

Also shoot short bursts, instead of single shots. Even with difficult subjects, chances are that if you take 3 or 4 shots in a fast burst, at least one of them will be in focus. (Also helpful with closed eyes and other momentary faux pas.... But I also try not to take too long bursts. I already have to spend too much time sitting at my computer reviewing images!)

Finally, you seem to be equating "tracking" to using multiple AF points, expecting the camera to switch AF points as the subject moves across your image area. Tracking also occurs when you maintain a single point on a moving subject, following it and keeping that point right where you want it. In AI Servo, the system is constantly updating focus, tracking and maintaining focus  How well it's doing this depends upon a number of factors: lighting conditions, subject contrast/detail, camera settings and AF system capabilities, lens focus system, lens max aperture, use of filters or teleconverters.... and user skill and experience.

When I "keep it simple"  with Single Point, dial in my camera properly, and am working with familiar moving subjects I get a very high "in focus" percentage. Probably over 98%. But when I'm shooting faster, more erratic and unpredictable or unfamiliar subjects, perhaps having to use one or another of the multi-point patterns, my percentages drop off a bit. That can't be helped. We all miss focus at times. I don't blame the gear, it's no fault of the camera or lens most of the time. Heck, more than once I've pressed the wrong button and ended up with AE Lock instead of focusing. Or I've quickly pulled the camera up to my eye to try to catch a shot, only to find I left it set with an AF point way over in a corner selected and have to take a moment to re-center it.

Many years ago I shot sports action a lot with manual focus lenses and cameras. I was darned good at it, too! But I can tell you for certain that today's AF systems are far faster and more accurate than I ever was doing it manually! 

Hope this helps.

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2) some other cameras, various lenses & accessories
FLICKR & ZENFOLIO 

[Waddizzle]

"You don't get to choose a "starting point" when using All Points/Auto. Think of this as a "point n shoot" mode. It basically leaves all the focusing decisions up to the camera. And since the camera doesn't have your brain, it will choose differently than you'd like a lot of the time. I never use All Points/Auto on . I tried it very briefly (around 20 years ago with EOS-3 film cameras)., but it gives up too much control for my liking."

I think you have a couple things incorrect.  Actually, you do get to choose the initial AF point when using alll AF points.  It is when you Use "Large Zone" AF, which allows you select the groups on the left right, and center, that do not allow you to select an initial AF point.

I have found this useful when I want to do Spot Metering on a subject that is not in the center of the frame.  Only Canon's 1D bodies allow you to spot meter with any AF point.  With any other body, you must use the center AF point for spot metering.  By metering with the center AF point, I can lock exposure.  As I recompose the shot AF tracking will move the active AF points in the frame, keeping the subject covered by an active AF point.

This technique also demonstrates the significant difference between AF tracking and AF focusing.  AF Focusing corrects focus as the distance to the subject changes.  AF tracking switches AF points to keep the subject covered by an active AF point as the subject moves around the frame.  Canon's high end bodes have very good AF tracking.

Also, there are two variations of the 3x3 array of AF points.  One mode does not allow you to select the initial AF point. I think this mode is called "Small Zone", and behaves just like its' bigger brother.  The 3x3 mode that you seem to use allows to select an AF point, and enable the 8 surrounding AF points.  They may look alike, but they work completely differently.

BTW, I learned the idea to use BBF as [AF-OFF] from a clever little man named Grant Atkinson.

https://youtu.be/7iP60Np0lpw 

He has series of 4 videos on the AF system of the Canon EOS 5D Mark IV.  The above link is to Part 1 of 4.  

https://www.youtube.com/playlist?list=PLJ2vrGUTJwXOf8d1DL8LjiLiZQN2bykph   (Grant Atkinson - 5D Mark IV)

I think Atkinson explains why he uses BBF for [AF-OFF] in the Part 4 video.  If it is not this camera, then maybe he explains in his 7D Mark II series videos on its' AF system.  I save BBF prograrmming as a Custom shooting mode.  In the regular Creative modes I use the default back button and shutter programming.

[EDIT]. Atkinson 5D Mark IV camera setup for wildlife photography - All Camera settings.

https://youtu.be/yy_72JQ-QT4 

[crockny]

Check out the YouTube videos of Grant Atkinson - there are many more options affecting your AF than you have mentioned.  He has a series of 4 videos where he gives very detailed explanations of what each setting does on the 5d Mark IV ... that way you can make informed choices in your setup for different situations ...

Ah I just saw the above post ... agree 100%!