Shoot perfectly focused photos every time by using an autofocusing technique called back button focus.
Back Button Focus: The Best Focusing Technique for Landscape Photographers
The ability to control your camera’s focusing system is one of the most fundamental skills that a landscape photographer should master, but focusing is often left to chance more than you might think.
Have you ever taken a blurry photo because your camera refocused right as you pressed the shutter button to shoot the image?
This is a common problem that photographers often deal with when using the shutter button to autofocus on their subject, but it is one that can be avoided by using a simple autofocusing technique called back button focus.
When you use back button focus to autofocus on your subject, you never have to leave focusing to chance.
Personally, I only shoot using back button focus, and it is a technique that I wish I had known from the start. I love it that much, and I think you will too.
In this article, you will not only learn what back button focus means, but also the most important reasons you should be using it.
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What is Back Button Focus?
For most digital cameras, the default state of the shutter button allows you to do two things:
- autofocus on a point within your composition
- shoot the photo
Autofocusing on a desired point of focus occurs when you press the shutter button down halfway, and the photo is taken when you press the shutter button down all the way.
At some point in your photography journey you may find that there is a problem with this method of autofocusing.
When you use the shutter button to focus and shoot the photo, the camera has to decide which of these two tasks to execute.
You usually shouldn’t rely on your camera make technical decisions for you.
Whenever the camera has to make a decision for you, you have to assume that it could make the wrong decision.
It is more practical and effective to assign one button to one task or function.
This way you can have greater control over each step you take when shooting a photo, and ultimately greater control over what your final image looks like.
The good news is that modern digital cameras give you the ability to choose the function(s) that you want certain buttons to perform.
This means that you can remove the focusing function from the shutter button and assign this function to a button on the back of the camera.
Back button focusing is a technique where the photographer uses a button on the back of their camera to autofocus rather than the shutter button to autofocus.
This button is usually the “AF-On” button which is typically located on the back of your camera as shown in figure 1.
When you use a button on the back of your camera to autofocus rather than the shutter button, you have effective assigned one function for each button.
- when you want to focus, you press the back button
- when you want to shoot the image, you press the shutter button.
While at first this may seem more complicated, once you try it, you will likely find that it is just as simple as what you are already doing.
It only requires a slight retraining of your muscle memory from what you are used to.
You will likely find that the benefits of this method far outweigh the default method for using the shutter for two different functions.
Why Should You Use Back Button Focus?
There are a four main reasons that I find back button focus to be better than shutter button autofocusing. These include:
1. Holds Your Focus
When you use the shutter button to focus, the camera will sometimes make the decision to refocus right before you press the shutter button all the way down to shoot the photo.
This can lead to out of focus images.
For example, imagine that you are out shooting and, after setting up your composition, you carefully focus on a particular point in your scene, such as the hyperfocal distance.
You have pressed the shutter button half way to autofocus on your desire focus point.
Noticing that your autofocus didn't focus perfectly (which sometimes happens), use the focus ring on your lens to manual dial in what your eye sees as the perfect focus.
Finally, after adjusting your exposure settings, you place your finger back on the shutter button and press it all the way down to shoot your photo…
but instead of immediately shooting the photo, the camera decides to refocus right before the image is captured.
Now you have an out of focus photograph because the camera made a decision incongruent with what you wanted.
This is a common scenario, and one that can be avoided by using back button focus.
When you use back button focus you can set your focus perfectly and then never worry about it changing.
Unless you are shooting a moving subject (i.e. wildlife) or focus stacking, most landscape compositions have a single, fixed focus point within the scene that won’t need to change once you have it set the way you want it.
Don’t let the camera decide to change the focus for you by using back button focus.
2. Holds the Exposure Settings
Just like you want to hold your focus, you also want to hold your exposure settings when you press the shutter button.
Holding your exposure settings when you shoot a photo is not a problem if you are in manual mode, but many landscape photographers, myself included, prefer to shoot in aperture priority mode.
This is a semi-automatic shooting mode that allows you to set your aperture manually and allows the camera to automatically set the shutter speed.
If you are using a shooting mode other than manual (e.g. automatic, aperture priority, shutter priority), the camera will meter the scene and adjust the exposure settings when you press the shutter button (or any other button) to autofocus.
This means that if you are using aperture priority mode, or any other non-manual shooting mode, and you press the shutter button to take the photo, the camera might decide to change the exposure settings right before the image is captured.
This is just like the problem described above when the camera decided to change the focus right before the image is shot.
For example, imagine that you have locked in the exact exposure settings you want aperture priority mode, exposure compensation, and the camera’s histogram (note: this is the technique I most often use).
In other words, you have your aperture, shutter speed, and ISO precisely how you want them in order to capture a perfect exposure.
When you press the shutter button to shoot the image, the camera not only decides to refocus, but chooses to change your shutter speed, too.This results in an exposure that you did not want.
If you remove the metering capability of the shutter button, you won’t have this problem.
By using a back button on your camera you can lock in your focus and your exposure settings before pressing the shutter button.
And once you do press the shutter to shoot the photo, none of these settings will change, resulting in an image exactly how you, the photographer, intended.
3. Faster Shooting Speed
What happens if you want to take a photo immediately but the camera has to decide between shooting the photo or focusing on the subject?
Imagine seeing a perfect, short-lived scene and not being able to capture it in the moment because the camera decided to refocus before the image was taken.
Fleeting light on a landscape or wildlife sightings are some examples of times when a landscape photographer usually wants to take a photo within seconds.
In the few seconds that it takes your camera to refocus, you could lose the perfect photo.
If you use back button focus, your camera will only focus when you tell it to focus.
The instant you press the shutter button is the instant the photo is taken, every time.
With back button focus, you decide when the photo is taken, not the camera.
4. Continuous Shooting Versatility
In virtually every landscape photograph I take, I use single-point autofocus (denoted AF-S for Nikon), which allows the photographer to choose the focus point manually.
Single-point autofocus is the autofocus mode that is best for landscape photography.
However, if you are shooting wildlife or any other moving subject, an autofocus mode called continuous focus mode (denoted AF-C for Nikon and AI Servo for Canon) can be very useful.
Continuous focusing mode allows you to focus on on your subject and, as long as you hold the focusing button down, the camera will track the movement of your subject, keeping it in focus.
This way, you don’t have to keep pressing the autofocus button every time your subject moves out of focus.
When you use back button focus, you can hold down the back button and lock focus on your subject while you are shooting your images.
You don’t have to choose between focusing and shooting. You can essentially do both at the same time.
This can be critical if you subject is moving quickly, such as an elk galloping across a field.
If you hold down the back button while in continuous autofocus mode, you don’t have to worry about constantly refocusing before you press the shutter button.
The beauty of back button focus is that it give you the versatility to choose between single-point and continuous focusing without having to change any settings.
You simply press the back button once if you want to focus on a stationary object, or you hold the back button down if you want to maintain focus on a moving object.
There is caveat worth mentioning here if you choose to keep your camera in continuous focus mode (AF-C).
I have heard some photographers report that single-point autofocus (AF-S) is more accurate than AF-C.
I personally haven’t noticed a difference, but I rarely choose AF-C and always use AF-S, simply because I only shoot landscapes (i.e. non-moving subject/focus point).
Some cameras might have more accurate AF-C features than others, so I would test it out to see if you lose some accuracy compared to AF-S.
If this is the case for you, I’d recommend that you choose a single, more accurate focus point using AF-S than let the camera lock on a focus point and potentially get it wrong.
How to Set Up Back Button Focus
Setting up back button focus is usually pretty simple, but the process will obviously be different depending on your camera make and model.
A Google search of “how to set up back button focus” plus your camera make and model should give you the information you need to set up back button focus on your camera.
I shoot with a Nikon D850, so I will walk you through the exact steps to set up back button focus on this camera. The process should be the same if not similar for other Nikon cameras like the Nikon D810, D800, D780, etc.
How to Set up Back Button Focus on a Nikon D850
- Press the “Menu” button on the back of the camera
- Scroll through the menu and select “Custom Setting Menu”
- Scroll through the Custom Setting Menu and select “Autofocus”
- Scroll through the Autofocus menu and select the “AF Activation” setting
- You will see two options: “Shutter/AF-ON” and “AF-ON only” You want to select “AF-ON only” - Note: By default, “Shutter/AF-ON will be selected. This means the shutter button is being used for autofocus.
- Go back to the Autofocus menu that you were on prior to set 5. The AF Activation setting should now be set to OFF.
Your camera should now autofocus via the AF-On button on the back of your camera.
If it’s not working, you will want to check to make sure that the AF-On button has been assigned to the autofocus function in the custom controls.
The AF-On button can be assigned many different functions, so you want to make sure it’s set to autofocus by following these steps:
- Press the “Menu” button on the back of the camera
- Scroll through the menu and select “Custom Setting Menu”
- Scroll through the Custom Setting Menu and select “Controls”
- Scroll through the Custom Setting Menu and select “Custom Control Assignment”
- Scroll down until you see the AF-ON button and make sure that AF-ON is set to AF-ON. If its not, select this setting and change it to AF-ON.
Downsides to Back Button Focusing
One of the only downsides that I have found to back button focusing - which really isn’t a downside - is that it takes a little bit of practice and retraining of your muscle memory before you get used to it.
Before you start using this technique, your instinct will always be to focus using the focus button.
It will feel awkward and unnatural to focus using a different button and then shooting your photos with the shutter button.
Re-coordinating the process of focusing and shooting - something that you have done countless times without thinking - will take moment to retrain your brain.
But honestly, it only took me about a week or two at the most to relearn how I focus.
You will pick it up very quickly, and then wonder how you ever focused any differently.
The benefits greatly outweighs the small learning curve, so I highly encourage you to try it.