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The autofocus of cameras now works wonders. But as fast as the focus works nowadays – here and there you still miss moments. The autofocus often causes the following problems at the decisive moment, which you surely know:
- You try to switch quickly between AF-S and AF-C, valuable seconds pass by
- At focus& recompose must be refocused on the eye for each photo
- The focus point has to be moved all the time
- The camera uses the eye autofocus, although you just want to take a picture of an object
For these problems, there is a simple solution that almost every camera offers: the so-called. Back button focus. What it is all about and how you can use it yourself you will learn in this article. Also in connection with the eye autofocus this technique is worth gold.
The focus disaster: one shot vs. AI servo
First, I want to briefly review the conventional focus methods and their limitations.
Focus and recompose for portraits in one shot mode
For years I used the focus and recompose technique for portraits. Say: for each photo, you move the focus point over the model’s eye, press the shutter button halfway, and then arrange the photo in the desired setup (recompose). Then you press your index finger all the way through and the camera releases.
This is repeated with every photo. Focus point over the eye, build up image, etc. If you were to watch the whole thing in time lapse it would probably look like you were shaking the camera back and forth all the time. With canon this is the one shot mode, which is designed for: focus once per photo. With other manufacturers, the mode is commonly known as AF-S, which is single autofocus stands.
For still portraits, you want to use focus and recompose to determine the composition of the image.
Follow focus on motion
Now let’s assume the model is on a catwalk and is constantly moving. He runs towards you and you want to take a picture. With AF-S and focus& recompose you will not get a sharp picture here. Because in the time you keep the shutter button half pressed, the person already moves out of the stored focus distance again. The photo will be blurred. Even if you press the shutter release button directly all the way down. In AF-S mode the camera focuses only once.
Therefore there is AF-C focus, what for continous autofocus stands. With canon this mode is called AI servo. With any camera this is the follow focus. In contrast to the static AF-S, the focus is recomputed several times per second, as long as the shutter button is pressed halfway down or the shutter button is released. Focusing is done. So if you now keep your focus field on the model’s face and the shutter release button half pressed, the focus is carried along.
In reportage and sudden movement, you need to quickly change the type of focus.
In this mode, the autofocus motor does not find rest, but constantly "updates" itself to the new position. This is how you can now photograph people in motion.
But beware: focus& recompose does not work here anymore. The focus would immediately focus on the background while rearranging the image composition as soon as the focus point deviates from the model. Instead, in AF-C mode, you must first place the focus point at the desired position in the image composition.
How to focus more relaxed and flexible with back button focus
Now we had photographed the model standing first (AF-S mode). Then the model has moved and we have photographed him while he is walking towards us (AF-C mode). So far it is logical and simple.
However, the following scenario is more difficult: the model enters the catwalk and stands still for a short time. Here we want a portrait with focus& recompose photograph. Then the model starts walking, and we want to take a picture while walking. At the end of the catwalk, the model then stops again, where we again have a focus& recompose portrait.
So the situation is quite tricky, because stand and movement are mixing. The problem is that you don’t have time to switch the camera from AF-S to AF-C and then back to AF-S mode. This wastes valuable seconds, causing you to miss the best moments of the catwalk.
The same situation is repeated in many scenarios: a soccer player, of whom you take a portrait only when he stands still for a moment. The next moment you take pictures as he runs away. Or a bride and groom who are standing in front of the altar for a portrait after the ceremony and then start moving for the procession.
How do you capture such situations reliably and quickly??
If you want to photograph static and moving subjects flexibly, you must use the back button focus.
This is exactly the kind of application that camera manufacturers have come up with (canon, by the way, already did in analog times). With the back button focus the shutter button no longer has two functions (focus + trigger) is occupied at once. Here the focusing is done on one of the back buttons (back button) is set and operated separately with the thumb.
On the back of my canon is the AF-on button for back button focus. alternatively, you can usually assign the focus function to the other buttons as well.
The release remains at the front of the shutter release and is done with the index finger as usual. A special feature is also that the focus is always in follow mode like AI servo or. Leave AF-C can be.
One shot (AF-S) is no longer needed for focusing and rearranging still portraits. Because now the camera does not focus on every release, but only separately via the back button.
For still photos, you can simply press the AF-on or AF-off button once. Back button focus. And then release the shutter an infinite number of times. As long as you don’t move, the set focus distance is kept.
I will now explain in more detail how exactly you can use back button focus for more flexible photography.
Here’s how to shoot static portraits and moving scenes with ease
Back to the initial situation: a model is not moving, you want to focus and then recompose the image (focus& recompose). For this you set z.B. Set the middle focus point as usual over the eye of the model, then press the back button once briefly. Now the focus is set to this distance and remains so. You can release the button.
The image can be arranged in the composition as desired, z.B. The model from the center to the right half of the photo. But you have to be careful that the distance remains unchanged, if necessary just focus again. But in and of itself, now that the focus has been set once, it can stay that way. You can now press the shutter button as many times as you like and you don’t have to focus on the eye every time again.
The shutter button is no longer responsible for the focus, which means that the set focus is no longer changed.
And now comes the force:
Does the model now (we remember, catwalk) suddenly start to run get every photo, even in motion – instantly and without interruption! All you have to do is to keep the focus point on the model as before. For the AF-C mode you hold the back-button now with your thumb. At the same time you trigger with the index finger. This works because the camera is already in AI servo or AF-C mode. Follow focus has been set. The difference is now only:
If the model moves, you hold down the back button. If not, it is enough to press once briefly and the focus remains.
Note: as long as the back button is pressed, the camera is in AF-C follow focus. By pressing the button for a short time, you shoot with the AF-S mode.
Ready! I know, you have to let this sink in first. I didn’t get it right away either, but it makes a lot of sense! It’s worth the change in any case.
Back button focus and eye autofocus combined
Just about all modern mirrorless system cameras now offer a pretty powerful way to shoot even more flexibly, more easily and more accurately at the same time.
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As I already described it in my article about the best hidden sony alpha camera settings, I would now like to summarize it again:
Also on the mirrorless you can use the AF-on button for the flexible back button focus. The autofocus has been removed from the shutter release and placed on AF-on. The camera is in AF-C or. AI servo mode. If I now press the button briefly, the camera focuses once. If I keep the button pressed, the subject is tracked. So far so good.
But the mirrorless system cameras now pretty much all offer the very powerful eye autofocus. With my sony this works better than I could focus on one eye myself. The function automatically detects the face and eye of a person, and focuses on them.
But if this function would be permanently activated, the camera would z.B. With many people on wedding reports quickly get confused. Or z.B. But focus on a person instead of the desired flower. Instead, I just want to activate this function specifically and at the right moment. And that without having to change anything in the menu first.
For this now a second "back button" is set, which doesn’t focus on the focus point, but on an eye.
Long story short: set the eye autofocus function in the camera menu under the custom button assignment z.B. On the AEL button on the back side. Now you can decide in a fraction of a second, depending on the situation: do you want to focus as usual on the selected autofocus area, or do you want to focus automatically on the eye of a person?.
Back button focus, only better: if I press the AF-on button, the camera focuses on the focus area as usual. If I press the AEL button, the camera searches for an eye.
Note: also the eye AF button sets the focus once when pressed briefly and tracks it as soon as the button is held down.
How to set up your camera
A small hook has the whole thing: the acclimatization. I myself have only photographed one shooting this way, which has worked quite well before. Today I pick up my camera again and wonder why it doesn’t focus. It just takes some time to internalize it. But I think it will be worth it!
Now I will show you the settings on my camera sony alpha 7 III and my former canon 5D mark III. With these settings it should be explained in general in the sony menu and canon menu – the settings can also be transferred to other camera manufacturers.
Set back button focus on sony A7 III
Now I’ll show you how to set the back button focus (together with the advanced eye AF button):
- 1. tab, page 6 of 14: AF b. trigger: off-> this is how the shutter button is only used to take the picture
- 2. tab, page 8 of 9: user key-> "set "AF-on" button to "AF on
- 2. tab, page 8 of 9: user key-> " radio. D. Assign "eye AF" to the "AEL button
- 1. tab, page 5 of 14: focus mode: tracking AF-> so the camera always stays in AF-C mode, short press of AF-on focuses once, press and hold to retighten focus
Back button adjust focus on canon 5D mark III
First go to the custom control menu and select the shutter release button. This is set by default to both focus (AF) and trigger. You deactivate the focus and set it only to trigger.
A short note on my own behalf: useful blog posts like this live only with some advertising. So with my lightroom presets you not only improve your post processing, but also support the blog at the same time:
in the canon menu under custom control you will find the option to assign buttons differently. Also with nikon there is usually such a menu item.
Here you remove from the shutter release the function to focus. What remains is that the exposure is measured and triggered.
To be able to take flexible pictures of moving objects, you can find the AI servo function under canon. With nikon this is called AF-C. This can also be left as it is for still portraits.
A special button is available for the back button focus on my camera and is called AF-on. here i don’t have to set anything, when i press this button, the camera focuses. If this button is not available, you can also assign the focus to one of the other buttons on the back of the camera. If you like you can set the focus mode to AI servo for canon or AF-C for nikon. This is handy in case the model might move suddenly. But it’s not a must, for standing still situations the one shot mode works as well.
If this is still a big mystery to you, you can find more information about the advantages and how to set it up on a nikon camera here:
Youtube always unlock
Tip for certain camera models: an alternative, which I have also set, is to switch between one shot and AI servo via a button. On the canon 5DIII for example the aperture preview button could be held down to temporarily switch to AI servo follow focus. by letting go it went on normally in one shot. The problem that you have to refocus 20 times for 20 photos with focus and recompose remains though. Also this assignment is not possible with every camera. For photos at very open aperture, it can still be handy to refocus for each photo now and then.
This "new" focusing in this way takes some getting used to, but will pay off in the end for most photographers. Especially when you z.B. More often photographing weddings, sports or other reportages. Situations where from being still (where you would like to photograph a composed portrait) a movement might suddenly follow. Here every second counts and these moments are not repeated. Either you have the photo, or you miss it. Back button focus is a super way to be flexible in such situations and combine portraits with photos in motion without delay. Most cameras offer this option out of the box.
If you want to know more, you can find everything about focus fields, eye autofocus and co in the comprehensive camera autofocus guide.
Pay attention to the crucial spots in the viewfinder and take better portraits immediately.
At free 7 days portrait email course sharpen your eye for coherent outdoor portraits. you get 2-3 tricks a day in the form of simple before and after photos. subscribe to the newsletter now and you will receive the course along with other useful tricks and offers for portrait photography.
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I am markus and I write from my experience as a professional photographer about the creative way of photography. I prefer to take portraits outside – in natural light. Because less is usually more. Every now and then I like to travel as well. When I’m not taking pictures, you can find me at metalcore concerts, in the nature or at the buffet. Be sure to check out my social media channels as well:
10 thoughts on "back button focus: with this button you simply focus more flexibly"
excellently explained. My compliments.
No one has ever described it so clearly.
With the fuji, it’s even easier once you figure it out.
Simply switch to manual focus on the lens. Now the camera doesn’t focus when you release the shutter, but the back focus button works:
tap for single AF and hold for AF tracking. Simply ingenious!
You can also work with crop and focus peaking and still adjust the focus manually. the loupe works too.
If the AFL button doesn’t work, it’s because of the activated face detection. You have to turn it off specifically.
Best regards and keep up the good work!
Sorry, small correction:
the switch for manual focus is next to the lens on the camera.
have your THO presets. P.S. These are great.
Question about the a7iii: do you have a tip for the eye AF in video mode?.
How do you recommend to act here.
The eye AF I can assign my knowledge only in photo mode of a button ..
We had already once contact by mail if I remember correctly 🙂 in video mode works as far as I know only facial recognition. I simply activate this in the FN menu beforehand if necessary – I haven’t tried out the button assignment yet.
I love your blog. You are the best so far in terms of photography explanations. Especially BF explanation here was just awesome. you go into the smallest details and really explain it in a very understandable way. I still have so much to read here on your site and I’m looking forward too. Please post more often and with pleasure also more from technics (objective, tips and tricks etc.).)
I think I will buy your e-book when I have time now.
Thanks for the kind words! I’m glad that the effort was worth it and the infos come across well. Thank you also for your support!
i shoot with the fuji xt2.
Where do you set the back button focus?
Search the net on how it works specifically for fuji. But in general, as with other models, first remove the autofocus from the shutter release (shutter release then only takes photos, whether sharp or not). Focus then back on the back button.
so far your post on back-button-focus is the best in terms of explanation. However, I still have a question: you are supposed to use the center focus point, which means that you really always have to have selected the center focus point manually in advance. Is this assumption correct?
It does not matter which focus point is used. The effect is the same in the end!
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