One-Shot vs. AI-Servo: When To Use Each

One-Shot vs. AI-Servo: When To Use Each


First off, this article would be called AF-S vs. AF-C if I were a Nikonian, they are the same thing so everyone gets to play! Don’t you wish they all just called everything the same thing? This is my second article to coincide with the sale of my ebook over at Snapndeals, DPS’s new sister site for awesome deals on photography stuff. If you haven’t checked out my ebook “Tack Sharp” yet, please do so!

So this question has been a really interesting topic for me for quite some time now: Which of these two focusing methods is the better method? Is there a right answer or do they each just have their specific time and place? Well, to start things off let’s first look at the key differences between these two main focusing methods.


This is probably the most commonly used method and is likely the ‘standard’ setting on your camera. When you press your shutter half way down (or use your AF-ON button instead which I go over in my ebook) the camera sets focus one time and holds that focal distance until the picture is taken. If you’re shooting still life or a subject that simply isn’t moving much then this is a good method to use. You can even go into your settings and make the camera beep when focus is locked so you know it’s good. This setting is also a must when using flash in low light; for whatever reason (I really wish Canon would change this) the focusing grid on your external flash will only work in One Shot mode. Switching to Servo will disable the grid completely.

For this shot of my son when he was just a week old I used One-Shot. I had a large reflector that I was bouncing flash off of so I made this choice for two reasons: One, because he was asleep and wasn't moving at all. And two because One-Shot works better when using flash (even though this wasn't really a low light situation)


Using AI-Servo was really a huge step forward for me . When I discovered it for the first time I was pretty blown away! AI-Servo tracks focus on moving subjects so as your subject moves closer or moves further away your camera constantly updates focus to keep the subject as sharp as possible. This means that a train could be headed straight towards you and you could set your center focus point over the nose of the train and your camera would keep the train in focus as it got close and closer. Eventually the train would be too close for your camera to focus though and at that time it’s best to get off the tracks (protip).

For this shot of two Blue Angels taking off I used AI-Servo. This was critical because the jets were obviously travels quite fast and with Servo I was able to track focus the entire time.

So Which One Is Best?

Well that really is the question isn’t it? Unfortunately there really isn’t a right answer. The better question is which one is better most of the time? And I will wager that the correct answer to that question is AI-Servo.

In my ebook I go over a technique that I started dling in conjunction with using back button focus instead of pressing the shutter half way down for focus. With my AF-On button set to focus I can use AI-Servo as both focus tracking and One-Shot. If I just need to set focus once and be done I can simply tap the AF-On button and then take the picture. If I need to track focus I can hold down to AF-On button while taking pictures.

I simply couldn’t do this if my focus was tied to my shutter button. Sure I could tap the shutter to set focus and then let go. But as soon as I pressed it down again to take a picture it would refocus. Hold the shutter button in limbo would cause Servo focusing to constantly track focus which is fine in some situations but not with a still subject.

So this method really just eliminates the need (in most cases) to have to switch your camera back and forth between One-Shot and AI-Servo. This is why 90% of the time my camera is set to AI-Servo.

When To Still Use One-Shot

There are still plenty of times when I’ll use One-Shot. Like I mentioned before, any time I am using flash I will set the camera to One-Shot so my flash will send out a focus grid in low light. Also if I’m shooting a any stationary subjects that aren’t moving much One-Shot is really the best option (or Live View with manual focus).


Well hopefully this article has helped you if you’ve never tried AI-Servo before. It really is an awesome setting and when used in conjunction with back button focus it’s game over. Let me know you’re thoughts in the comments and feel free to ask questions.

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James Brandon is a landscape photographer and educator residing in Dallas, Texas. Join 20,000+ photographers and get access to his free video tutorial library at his website. James also has an online store full of video courses, ebooks, presets and more. Use the coupon code "DPS25" for an exclusive discount!

Some Older Comments

  • Paul Schendel May 24, 2013 02:10 am

    This is an embarrassing question but by BBF do you mean the AF-on button on the back of my Canon60D? Or is there another button that is easier? I do some copy work for local artists and I find that for still shots that the auto focus is not quite as sharp as going to manual focus and then using the magnify button and tweeking the shot. Is there a problem with the autofocus on my camera? Thanks for your help and your great article

  • Mackenzie May 16, 2013 06:23 am

    Sorry, I am confused. I use a Nikon; what is Al Servo on a Nikon?

  • dennis n April 9, 2013 02:17 pm

    Thanks for the great article!
    I wanted to take professional looking pictures during a recent Formula 1 race. It was really exasperating - not being able to get a good shot despite having chosen a nice spot. The subject here (the cars) were closing in just too fast for my AI SERVO to keep up with. I then set my focus on a spot on the track and selected manual focus, shot pictures with continuous shooting... this finally worked for me. Didn't use a tripod either. But then it took me at least 200-odd shots to get down to a fair success rate!

  • Jenny R March 27, 2013 12:58 am

    The day I read in the manual for my Canon 1100D what AL Servo does was the turning point for my photos of birds, butterflies and small animals! That's mostly what I photograph.
    I leave my camera set on Al Servo all the time.

    (ps I've always taken it to be AL Servo but that sounds like a greasy diner)

  • James Brandon February 13, 2013 03:48 am

    Robbin, where did you get that link? Guess I still have a bad link somewhere. That page is now You can send instructions to me at contact(at)james-brandon(dot)com. Thank you!

  • Robbin February 10, 2013 09:05 am

    Hi. I was going to put up the instructions for the 6D (since I finally figured it out!! but I'm getting a 404 on (

    And I have always found the 1/2 push shutter button focus to be annoying. I love, Love, LOVE these methods from your eBook "Tack Sharp". The AF-ON button is in the perfect spot - almost like it was designed that way! I just figured it out last night and am working on making it second nature, but the camera is only a week old so I think it won't be too hard of a shift as this camera is so different from my previous ones. I'm already seeing improvement in my focus. Not so much on the back of the camera or even internet, but definitely when zooming in on Photoshop!

    Thank you!!!

  • Marcum Yates October 1, 2012 01:48 pm

    James, I purchased your book "Tack Sharp" and it has improved the focus in my photos of all things mobile; it also makes shooting stationary subjects less of a pain as well using BBF to lock in focus on multiple shots.

    I'll speak for Nikon since most of this BBF discussion has been mostly on Canon.

    I use a Nikon d7000 and a d3100 with BBF. The menu for the 7000 was easiest to set this up, just go to the custom menu f 5 "Assign AE-AL button" and scroll down to and click AF-ON and you are good to go.

    The d3100 menu is simpler but less defined (this may work for the d5100 too); in the menu, go to the wrench icon, scroll to "Buttons," click OK, then scroll to AE-L/AF-L Button, click OK, scroll to and click OK on AF-ON and you now have BBF using the AE-L/AF-L button.

    This weekend with my d7000 I shot some large model aircraft (8 to 15 ft wing spans), and smaller craft, as they took off, in flight, and landed, and got the majority in focus by using AF-C and BBC set on dynamic 9 point focus which clusters the focus points at the center, or where you want it (left or right) in the frame for off-center focusing. Composition is hard to hold and hold the camera steady, so I keep the focus in the center and frame to allow room for a little cropping to get the composition I wanted. I noticed on take-offs and landings that any other object between the camera and aircraft stayed out of focus and the model was in focus as it moved past them.

    BBF may not be everyone's preference, but I have found it to be much better to separate focusing from the shutter button. It will take a while to get accustomed to this, but it was a short learning curve for me.

  • Raduy September 30, 2012 02:28 pm

    do you have any tips with when using flash I have a 5D MII

  • Raduy September 30, 2012 02:27 pm

    thaaaaaank you very much!!!!!! I couldnĀ“t understand why the grid suddenly disappeared when focusing with the flash!

    so for moving things you set to Ai Servo and focus with AF-ON? and the camera will keep track of the moving subjects focus? this is correct?

  • David September 29, 2012 11:07 am

    Two words for BBF - no brainer. Read your previous article on BBF and the various doubters in the comments. Set my Canon up for it and headed out the next day to try it out. I won't be switching back. And I'll be setting up AI-Servo and heading out tomorrow. I'm sure I'll be just as happy with the results. Thanks for the article!

  • Hendro Heryanto September 29, 2012 10:28 am

    There is AI Focus besiide AI Servo in most of Canon Camera, what is its function & what difference with AI Servo ? Thanks.

  • egrubbs September 29, 2012 12:58 am

    is back "button focus" the same as AF/AE Lock?!? I have a Nikon d5100 and I CAN NOT figure this little button out! I started exploring it a week ago (i even posted a question in the forums) but i can't seem to see what it is doing... lol...i am beginning to think mine is broke! ;-) i've read and read and i "think" i understand how it should function....but does anyone have an "experiment" that will show me its capabilities? i.e. take a picture with it and then another picture without it and then compare the two to see the difference.... thanks guys!! ***Thanks for the post james! it all made sense- except for the one paragraph on back-button focus. And btw, beautiful little boy! We are celebrating our son's 2nd birthday in a couple months...time flies... :-(

  • marius2die4 September 28, 2012 05:11 pm

    On my camera (olympus) I have a type of focus for moving subjects (the focus follow the subject) and another one for static subjects ( camera make the focus at some distance and stay there).

    Some of my pics:

  • Bill R September 28, 2012 02:38 pm

    Got this shot last weekend when they were here. Used AI-servo

  • Tim Roper September 28, 2012 01:47 pm

    Great tip that I think will also help with focus and recompose when doing multiple frames of the same subject and composition (won't have to go back and focus each time). That's been a big pain for me, and this sounds like a better solution than having to keep the BBF pressed the whole time while pressing the shutter, too.

  • James Brandon September 28, 2012 01:32 pm

    Zvika - I'm not a big fan of AI-Focus. It's supposed to be a hybrid that automatically switches between Servo and One Shot but it doesn't work very well.

    Jerome - Thanks for the kind words, I really appreciate it!

    Joe - You should be able to still set the * button to BBF.

    For anyone reading this who has read my ebook and set up all the settings I go over on a camera different from the Canon 5D Mark II - head over to my website and read the bottom section of this page ( I added a new section where I hope to add instructions for as many other cameras out there as possible. I'm hoping those who have applied these techniques to their camera's are willing to do a quick write up on how to do it on their camera since I can't answer that question for every camera out there.

  • Joe September 28, 2012 12:12 pm

    Excellent write up on this topic.

    It works great if your camera has AF-ON button, what if I don't have one? How do I use AI-Serve effectively?

    I'm using Canon 600D.


  • Bill M September 28, 2012 12:09 pm

    Just started using BBF. Plan on using it for a wedding in November. Any advice for single vs. Servo mode?

  • Janet M September 28, 2012 08:35 am

    I read your article on back button focus and decided to try it and now I'll never go back to using the shutter button. I use Al-Servo most of the time since switching (I used to mainly use AF-A) and the vast majority of my action shots are in focus.

  • Jerome Boyer September 28, 2012 08:31 am

    Thanks for the sharp article. I just bought your ebook. Highly recommended, imo.

    Your training strategy is very pleasant and I found I could read the 45 pages or so non-stop, getting a few excellent tips on the fly.

    Keep the good work!

    PS: I wish camera defaults would be central focus point, AI Servo; many forums are littered with: my 7D does not focus etc... When using that strategy and never focusing and recomposing always gives the best results.(I own a 7D)

  • Jim Woolsey September 28, 2012 05:53 am

    Great Post! I like the newborn pic. I find that I switch between AF one shot and servo when doing newborn photo shoots because some babies are movers and others are not! I definitely prefer one shot but I use servo a lot when shooting weddings, especially during the ceremony when the wedding party, bride, groom etc. are walking up or down the isle.

  • Zvika Shiffer September 28, 2012 04:33 am

    hello, thanks for the tip; i was aware of the AI-Servo functionality but keeping it as permanent (almost) setting and use the AF_ON was completely new to me, thanks again.
    can you sortly comment on using the AI-Focus setting vs. the One shot? (Yes, i own a Canon)...The manufecturer claims that this setting should automatically switch the focus mode if the subject is moving...

  • Frenchy Smith September 28, 2012 01:38 am

    I have started using back button autofocus on my 5D Mk II, it has worked like a charm. I was having some focus problems especially in low light or low contrast situations, but now it works really well.

  • James Brandon September 28, 2012 01:11 am

    Jason - If you don't see the value in it then don't use it. Have you tried setting it up yet? One common thing that I hear a lot from doubters about this method is that separating the focus from the shutter is just adding an extra step and therefore increases the time it takes to take a photo. If I had to reach for the AF-ON button at all this would be true. But the fact is that my thumb rests on top of the AF-ON button now. I think before my thumb probably rested between the AF-ON and the joystick but now my thumb rests about half on the the AF-ON just underneath it. So when it's time to focus on something I just roll my thumb over slightly. It takes no extra time at all because focusing is the first step towards taking the picture.

    The numerous additional advantages I've explained several times in my past articles and in detail in my ebook so I won't go into them here in a comment.

  • Scott September 28, 2012 12:49 am

    You can actually use both modes simultaneously if your camera is set up for back button focus.

  • Adidas Wings Jeremy Scott September 27, 2012 03:37 pm

    Thanks for your post. I also believe that laptop computers have gotten more and more popular lately, and now in many cases are the only type of computer found in a household. This is due to the fact that at the same time actually becoming more and more very affordable, their working power keeps growing to the point where these are as robust as personal computers out of just a few years back.

  • shawmutt September 27, 2012 10:56 am

    All these wonderful settings on my camera, so little time. Thanks for blogging this, another setting demystified!

  • Jason St. Petersburg Photographer September 27, 2012 10:18 am

    Actually, camera manufacturers do all call focus mode the same (AF-S & AF-C), it is only Canon that uses something different. One of the reasons I chose a Nikon D300 was for its extremely convenient and easy to use focus mode switch which allows blind and instant changing between focus modes. Unfortunately, newer Nikon models have the switch in the same place, but it is no longer so easy to toggle between AF-S & AF-C.

    I coincidentally just put up this same photography tip on my own site today: No matter how many times I read about using the AF-ON button, I see no advantage to it. And, I almost never go back and forth multiple times between shooting moving & still subjects. The only time I have consistently done that is when shooting baseball. In that situation, I used AF-C and the AF-L button, and would use that combo before using AF-ON.

  • Kiran @ September 27, 2012 09:06 am

    I've never heard of Al-Servo before. Off to do more research, thanks for the article!

  • Albin September 27, 2012 05:01 am

    Good of you to call attention to this feature. When shooting action I tend, where possible, to try to set DOF to let me lock focus on a fixed object where I anticipate action, like a phone pole the racing bikes will pass, instead of trying to fix on a moving subject. I've never had a good sense of what speeds or angles of motion (Canon) Servo will work well on.