The Power of Back Button Focus in Wildlife Photography

Andrew Beck All Authors, Andrew 42 Comments

This post is getting some great traffic and I am glad to see that so many people have been inspired to try this technique. One of the benefits of this setup which I forgot to mention is the fact that it simultaneously allows you to switch into manual focus without having to change the AF/MF switch on your lens. This has come in handy for me in situations where I my subject is not easily picked up by the camera’s AF system or when I want to make subtle adjustments to my focal plane.

Something to keep in mind!

I have also completed the follow up post on how to setup back button focus on your camera here.

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The need for this post arose after a Masterclass Presentation which I ran on “Depth of Field in Wildlife Photography” during which I emphasised the importance of achieving correct focus on your subject. If your focus point is not where it should be then you cant expect the resultant depth of field to fall in the correct plane either.

When I asked the question of who has heard of and uses back button focussing on our Facebook Page, the responses ranged from “I have no idea what everyone is talking about…” to “Back button focussing doubled my keeper rate. I can’t live without it now”.

Personally, I think there are a lot more people who have no idea about back button focus and were to afraid to say, so – lets sort that out!

Let me start off by clarifying that back button focus is not to be confused with back focus or rear focus issues. Back focus is when the camera/lens combination focuses behind the intended target, and back button focusing is a technique which separates the focus and shutter activation of the shutter button.

Normally, when you half depress your shutter button, the camera engages the autofocus and achieves focus on your subject, with a bit more downward pressure on the button the shutter is tripped and the image captured. With back button we are taking the autofocus process away from the shutter button and re-assigning it to another button on the back of the camera. No points for guessing why its referred to as back button focus!

The other important consideration in this whole topic is the choice of focal points. Most wildlife photographers spend the majority of their time using only the central AF point – regardless of camera brand or model. This central focus point is almost always the most accurate and sharpest of all of the focus points. The issue with this is that most compositions don’t work with us focusing in the middle of the frame. Yes you can shoot in One Shot/AF-S and recompose or use the AF Lock feature but how much time do you spend in One Shot/AF-S as a wildlife photographer?

What if I told you that you could stay in AI-Servo/AF-C but still focus and recompose as if you were shooting in One Shot/AF-S?

A potential game changer right?

Picture this, you head out on drive and come across this scene:

Back Button Focus

The pair stand up and start to move down the river bed towards you, so you immediately set your camera into AI Servo or AF-C so that your autofocus is continuously tracking their movement and compensating accordingly.

Back Button Focus-3

The pair suddenly stop and start to mate. From a composition point of view, your central focus point is spot on and for all intensive purposes, you should probably switch back to One-Shot/AF-S as the pair are no longer moving. Not ideal because you don’t want to take your eyes off of the action, and they will in all likelihood continue to move once they are finished mating. You stick with your central focus point and AI Servo/AF-C and wait for the critical moment.

Back Button Focus-4

In a fraction of a second, the male raises up and twists to the right of frame. Your focus point no longer rests on the subject and falls on the bush behind the pair.

Back Button Focus-5

You are rattling off frames as the camera continuously re-adjusts the focus between each shot.

Back Button Focus-6

As the moment comes to a dramatic climax, the male snarls and bares his teeth, your focus point is nowhere near his face.

Back Button Focus-7

The final images are soft.

The focus point was not positioned accurately and the resultant depth of field was not enough to render the subjects sharp and completely in focus.

Knowing that back button focus separates the engaging of the autofocus function and the activation of the shutter, this scenario could have played out very differently. Lets look at how it would have worked with back button focus setup.

  • The Lions are moving in the river bed >> central focus point, AI Servo/AF-C with thumb on back button to continuously track movement
  • The pair stops and starts to mate >> Achieve focus on the male and dial in an aperture which gives a bit of extra depth of field, thumb off back button, finger on shutter to pick shots at crucial moments
  • Male twists and turns off of central focus point >> thumb still off back button, focus remains as is, as does resultant depth of field, finger on shutter to pick shots
  • Pair get up and walk towards us >> thumb returns to back button, AF engaged, finger on shutter to pick shots

Because I now have the ability to decide when to engage or not to engage the AF mechanism in the camera, I can essentially use the camera in both One Shot/AF-S and AI Servo/AF-C at the same time.

Make sense?

Here’s a more simple example.

A lioness is approaching a herd of wildebeest in the Masai Mara.

I track her using my central focus point in AI Servo/AF-C mode and back button focus setup. As she moves between the long grass I keep my thumb on the back button, forcing the autofocus to continuously track her movement and keep her in focus.

As she gets closer to the herd she stops and stares. From a composition point of view I certainly don’t wait her in the middle of my frame.

Using my thumb I achieve focus on her before releasing the back button (note that I am still in AI Sservo/AF-C mode in case she starts to chase or stalk again) and recomposing with her to the left of frame. I trip the shutter with my index finger.

Back Button Focus-8

She inevitably starts to move again and, without having to change camera settings at all, I am ready to place my thumb on the back button, track her, and capture any action that takes place.

There are of course other ways to work this situation:

  • Changing to One Shot/AF-S (usually requires you to take your eyes off of your subject and you would need to change back to AI Servo/AF-C when your subject moves again)
  • Cycling through your selected focus points (This can be time consuming, confusing, and your other focus points may not be as accurate as your central focus point)
  • Holding the AF-L, AE-L button (this works for some people but I am personally not a fan)

Hopefully those of you who joined me for my Masterclass presentation will be sitting there knowing that Back button focusing is superior in this instance as long as I was careful not to change the distance between the camera and the subject (which would throw off the focus) as I was using a shallow depth-of-field.

This is one of a handful of things to keep in mind.

Things to keep in Mind:

  • If shooting at a shallow depth of field (eg F2.8), or if you are shooting a long lens in very close to your subject, be wary of re-composing a shot as your focus plane can change dramatically. In those cases, you will want to only use an auto-focus point that is DIRECTLY over the area you want in focus, and then do NOT re-compose your shot.
  • Spend time practicing this method as you need muscle memory to do this naturally. You DON’T want to try this out for a wedding unless you have used it for while and feel comfortable with it!
  • The camera will now take images even if you have NOT achieved focus. So, don’t assume a shot is in focus just because your camera takes the picture.
  • Following on from the above, remember that when someone else grabs your camera to take photos, they will more than likely not know how to engage the autofocus!

So hopefully you have a better understanding of what back button focus is and how it can be used in your own photography. Remember that this is by no-means the only way to do shoot. But it certainly has helped me to improve and streamline the settings and though processes before taking an image.

Tomorrow I will follow up on this post with how you can go about setting back button focus up on your camera!

Andrew Beck

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About the Author

Andrew Beck

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Very few people can tell you what their passion in life is. Even fewer will be able to tell you that what they do for a living is in fact their passion. My love for the bush and conservation took me on journey which would not only allow me to explore the continent which fascinates me so much, but to share my passion for photography and conservation with others. Be sure to check out my my website and instagram account.

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Comments 42

  1. Karl Lindsay

    Great post Andrew… the other thing I love about back button focusing is perhaps more useful in landscapes, but for wildlife too when the subject isn’t moving. It gives you the ability to focus and recompose… or better yet.. focus (with back button), expose for correct area of image (with half press shutter), and recompose and shoot. It’s like the nice iPhone apps that let you choose your exposure point separately from the focal point.

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  2. Carol Bell

    Thanks for this Andrew…. just cannot wait to read the rest tomorrow. I have never heard of this before…. I did not even know that other focus points may not be as accurate as my central focal point.

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      Andrew Beck

      Hi Carol

      You are so right, it is something which is not often talked about and shared. I have no doubt that you will enjoy using this technique even though it does take a bit of getting used to!

  3. Chetan K Jain

    Andrew, Great post … one clarification please.

    When you mention – as the lioness is moving, thumb goes on the back button so you keep tracking her, now if I want to take a shot while she is moving, I will get the lioness in the center of the frame. But suppose I want to apply the rule of third .. how do I handle this situation?

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      Andrew Beck

      HI Chetan

      This can become an issue and there are really only two ways to fix this:

      1) A slight crop in from the left to give you your desired composition. More often than not in these instances the subject dominates the frame so only a slight crop is needed to achieve the desired result.

      2) Manually select one of the focus points which would give you your desired composition. This is a good bet if you are not expecting any dramatic action and rapid movement but can be tricky if you start to introduce these aspects or multiple subjects interacting with one-another.

      I must also say that the top end cameras now have AF scenarios and are far better equipped to track subjects by automatically selecting the focus points and this would also address your question of composition.

      I hope this helps?

  4. Sue Jarrett

    Very interesting! May I make one offer? You have to set “back button focus only” in the camera menu.

    When I first heard about this, I tried just focusing with the back button tracking a deer – focus spot on head. Shoot, shoot. Deer stops, hand off back button, focus spot on head, shoot, shoot. Deer turns his head and focus spot off — out of focus. Why? Pushing the shutter button focused on the bush behind him. Focus wasn’t locked to just the back button keeping his head in focus..

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      Andrew Beck

      Hi Sue

      You are quite right – you need to assign the AF function to the back button only. As I mentioned in the bottom of my post, I will be sharing a post on how to set this up on your camera shortly.

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  5. Barry

    Hi Andrew,

    Have you ever tried the option of re programming the DOF preview button to enable switching between one shot AF and AI servo? I’ve only just discovered this since getting the my 70D (don’t think the 40D had this option), I don’t think I would use it instead of back button focusing because of how inaccessible the DOF Preview button is but possibly in conjunction with it could be handy at times to quickly switch to single shot AF and then just let go of the button to resume AI Servo. I’m going to have to play with it a bit before i know if it is useful or not. What are your thoughts?

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      Andrew Beck

      Hey Barry

      Thats a nifty feature and its really only the newer models that allow you to assign a custom function to the DOF preview button. It’s not something I’ve thought about doing because I am so comfortable with my current setup but its an interesting thought.

      It may be handy if the button switches between the AF drives (eg from AI Servo to One Shot) but if you need to have it depressed you then have 3 fingers (thumb, index and an additional) controlling functions – could get messy!

      Try it out and let me know how it works – will try it for myself too!

    2. Robin Hoskyns

      I have a 7d and it’s very annoying that this can’t be assigned to a more accessible button! A one touch function to switch between one-shot and AI-servo that could be customised to the multi function button next to the shutter would be great!

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        1. Robin Hoskyns

          It would be so easy for them to do. You can set it to a button on the lens (but obviously only if you lens has a button on!) or to the dof-preview button which is on the wrong side of the camera!

  6. Robin Hoskyns

    On my 7d I use the “AF-off” button in similar situations. It pretty much amounts to the same thing without you having to spend a lot of time getting used to full on back button focusing. The only thing is you have to remember to keep your thumb on the button or press it before pressing the shutter button.

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      Andrew Beck

      Hi Gerhard, I am almost 100% sure it can be done. I am following up this post with a post on how to set this up on both Canon & Nikon systems and will post the link here for you once its done.

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  7. Irene Amiet

    Thank you for the tutorial, Andrew. I wonder sometimes if I’m the only wildlife photographer who shoots in manual mode with anticipating movement. Such as the lion jumping off. That way I keep control over the lighting as well. Let the eye do the job over the camera. Because in the first instant you end up with clear shots but the whole of the image has only documentary value. I don’t want to see the bush behind them at all.
    But regardless, great explaining, cheers

  8. Mike Smith

    I have read a few similar articles about using BBF and I see the value in it, but I can’t bring myself to change just yet based on my current camera body. I’m using a Canon 40D with a battery grip. I can change to BBF on the camera body itself, but the grip does not have a button that I can programed for back button focusing. I’m wondering if anyone else is dealing with this issue, or perhaps knows of a way to set up a camera with battery grip so this isn’t a problem.

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      Andrew Beck

      Hi Mike

      The battery grip may not have a dedicated AF button for back button focussing but you should be able to assign this function to the Exposure lock button ( * ). I will expand on this in the follow up post which i am putting together today.

      I must say, I haven’t wanted to use AI-Servo in portrait orientation that i can remember though.

  9. Greg Vaughn

    Excellent article. A great tip and really well written. I decided to give it a try and discovered that, for me, it works better on my cameras (D600, D300S, D7100) to program the Fn button to do the focusing. I can keep my ring finger (3rd finger) on the Fn button, index finger on the shutter and thumb on the main command dial, and still maintain a good, solid grip on the camera.

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      Andrew Beck

      Hi Greg

      Glad to hear that you’ve found a system that works for you! The newer camera bodies are coming out with some fantastic custom function settings which will allow more and more of these unique combinations to be setup exactly as the photographer wants them.

      I guess the companies listened to all those times photographers cursed and said “You know what would be great, is if there was a button over here that controlled…”

      Thanks for sharing with us and taking the r!me to comment.

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  11. Peter Connan

    Thanks Andrew
    I have been using this technique for a while and also wonder how I got by before. Since my wife also uses my camera on occasion though, and doesn’t want to use BBF, I have it set up only on the two “user modes” of my D7000. That way, changing to any of the other modes puts it back on shutter-button focus.

    However, you make a very valid point about (not) using it with wider-angle lenses as the focal plane shifts. Is there a rule-of-thumb regarding focal length and aperture beyond which you would rather move the active focus point?

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    Andrew Beck

    Hi Peter

    Thats one way to make sure your wife doesn’t use your camera! 😉

    With regards to the recomposing and the change in focal plane – I haven’t come across anything but, off the top of my head, I would think this would be most important when working in close proximity to the subject or with telephoto lenses as the effective depth of field is dramatically reduced by an increase in focal length and a decrease in the distance between the camera and the subject.

    I hope this makes sense?

    You might find this post useful though: http://photography.wild-eye.co.za/cant-afford-f2-8-lens-try/

    1. Peter Connan

      Andrew, thanks for replying.
      I went and did some calculations and I conclude that the focal length of the lens plays almost no role in this. A wide variety of focal lengths (from 15mm to 800mm give virtually identical results, but very short focal lengths do skew this slightly) give almost identical results.

      The important factors are aperture and object distance. I did a calculation to determine the minimum focus distance at various f-stops, and the results look like this:
      f1.4: 10.4m
      f1.8: 8.1m
      f2.8: 5.2m
      f4: 3.6m
      f5.6: 2.6m
      f8:8m

      Keep in mind that these calculations take depth of field in mind, and thus the results are only a guideline,depending on how critical the user is to sharpness.

      If you are interested, I can explain the calculations and the assumptions behind them?

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        Andrew Beck

        Hi Peter

        I think we are on the same page here apart from the focal length side of things. If you are photographing a subject in close proximity with a 200mm f2.8 for example, the resultant depth of field is so shallow that even the slightest change in distance (either through recomposing,the subject moving, or you as a photographer moving) will have an impact on the final result.

        I’m not sure if you have ever seen or used DOF Master?

        http://www.dofmaster.com/dofjs.html

        1. Peter Connan

          Andrew, while I don’t argue for a moment that the depth of field on longer focal lengths fast lenses is very shallow, the longer focal lengths tend to have two things going for them in this regard.

          Firstly, the longer the focal length, the narrower the angle of view, thus the angular change from the centre focus point to the edge of the frame is very small, and therefore the change in focus distance is also small, and secondly they tend to have relatively longer minimum focus distances.

          If you send me your E-mail address, I can send you some drawings to illustrate what I mean?

  13. Paul Samuel

    So I’ve just pulled out my camera, set it up for BBF and I’m playing scenarios out in my head. Now that I get the mechanics thereof, I’m starting to see tremendous potential for improving my photography.

    Andrew, quick question: Am I correct in thinking that aside from the initial button tap to focus, the only other time to do so would be when the subject moves in or out of the focal plane (Z axis)?

    And on that point, would you keep your finger on the assigned BBF button if the animal is moving erratically?

    Thanks for the education Andrew, much appreciated!

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      Andrew Beck

      Hi Paul

      Glad you fond this helpful. You would need to keep your thumb on the button whenever you need the AF to engage so when a subject moves or changes position you will need to engage the autofocus and track your subject. Thats the beauty of being able to be in AI Servo mode all the time.

  14. Matt Mckean

    Great article… I recently bought a canon 200-400 and coupled this on my 7d.. I thought I could just head out and use the camera the same as I had been in the past but couldn’t get the sharp images I expected.. A few people said about back button focusing but I didn’t really see how it could be better until today when I noticed how sharp images were when I took on one shot but found it to much hassle switching between this and continuous AF every other second.. I fiddled around in the menu and assigned the back button to focusing and meter (as per your follow up article) and I had a light bulb moment, sharp image after sharp with the ability to have the best of both worlds all under one button.. It really seemed a game changer and feel much more confident now heading out to India that tigers will be photographed and sharp images will be had.. I must say though, I didn’t know most wildlife photographers used centre focus only, I’ve never used it and always used the af point where I wanted to place the subject in the frame as centre focus and recompose seems to long winded for a subject that could move at any given moment and post cropping an image to gain composition seems a little backward. I do however appreciate the centre af is the sharpest and most sensitive. Thanks again for a great article..

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      Andrew Beck

      Hi Matt

      Stoked that you have found a solution to your problem and that you’re getting the results you are after. The selection of the focus point is a personal preference and does depend on the scene you are photographing but my personal preference is to use this central focus point and then re-compose given the fact that i can disengage the AF system with the back button focus setup.

      I hope you’ll share some of your images from India with us – the Tiger is still on my list of big cats to photograph.

      All the best!

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