What is AF in photography?
AF stands for autofocus in photography and is a feature of all modern cameras. Mirrorless cameras have the advantage over DSLR cameras of auto eye AF, which detects faces and focuses on the eye automatically, which is incredibly useful for portrait photography. However, the AF system of DSLR cameras have AF options for sharp focus.
New photographers get confused about AF in photography, because there are different focus settings, which I’ll explain in this article. They are:
- Autofocus area mode (AF area mode)
- Autofocus modes (AF mode)
How to use your camera’s autofocus modes properly
Your DSLR camera is designed to take sharp photos, no matter whether it’s an entry level camera or top of the range. If you’re not getting sharp photos, it’s probably not because there’s something wrong with the camera. Most times it’s just learning how to use focusing modes and autofocus area modes properly.
Just because it says autofocus on the tin, doesn’t mean that your camera automatically focuses on the right part of the photo.
Don’t be tempted to take the easy focus route
To master photography, the best thing you can do for yourself is not take the easy route. In many ways I think we’re at a disadvantage with our high tech cameras these days. Because modern cameras are so clever, we don’t need to be. They make it too easy for us to pick one up and start photographing.
When you first pick up your camera you’ll photograph anything and everything… just so you can take a photo and play with your new toy. This is the best time not to go the easy route (or what appears to be easy), because it’s actually the long way around to getting a good photo.
You need to understand how focus works – manual focus and autofocus.
When I say easy route, I mean auto, but I’m not talking about manual focus versus autofocus. I mean auto mode – some beginner photographers get auto mode and autofocus mode confused. Auto mode is a camera setting that does everything for you in terms of exposure and also decides on where to focus. Autofocus is just for focusing.
I hardly ever use manual focus, except for low light photography when the camera has a hard time autofocusing even on stationary subjects. Why would I when autofocus is so awesome?
Well, except for these times… The 9 times manual focus beats autofocus
But back to how to use AF in photography properly. At first we assume that the camera will just focus for us, we think that’s all there is to it. It’s misleading.
To make the most of your camera’s autofocus abilities, you need to be out of auto mode. If you’re not comfortable with aperture priority, shutter priority or manual mode, use program mode. It’s like auto mode, but better.
Your camera’s default autofocus setting is not great
Focus is one of the biggest stumbling blocks when people first pick up a camera. Using the default autofocus mode on your camera is partly why it’s a problem. This is for two reasons:
- You can’t get the right focus, because your camera is not a mind reader (despite what you paid for it)
- You don’t know the best focusing mode to use for the situation (yes, there’s more than 1)
The good news is that there’s a really easy fix. You just need to know the two steps to every autofocus decision and then practice.
The two step autofocus decision:
You need to answer two questions to make your autofocus decisions:
- Is my subject moving / about to move, or is it still? This decides the autofocus mode
- Where do I want to focus? This determines which autofocus area mode to use
Let’s look at these questions and their answers in greater detail to understand how to use autofocus properly.
There are three focusing modes:
- Manual focus (MF)
- Continuous autofocus (Continuous AF)
- Single autofocus (Single AF)
As we’re talking about autofocus in this tutorial, I won’t discuss manual focus mode here.
1. Autofocus mode decision: Is it moving?
Depending on what you’re photographing, you can select one of two AF modes:
- Focus continuously
- Focus once and hold
The key to accurate focus every time is understanding and using the correct autofocus mode for different subjects.
Because terminology differs between brands, I’ll mention only Nikon, Canon and Sony in this tutorial, as they’re the biggest brands. We’d all get very bored if I ran through every camera make each time… and I couldn’t possibly know them all.
Continuous servo AF for focusing on moving subjects
If your subject is moving, switch to continuous servo AF – in other words, continuous focus.
- AF-C (Nikon and Sony)
- AI Servo (Canon)
To use continuous autofocus mode:
- Part depress the shutter release button (aka the shutter button) for the camera to autofocus
- It will continue to adjust focus on the main subject if either you or your subject moves while you’re holding the button part way down
- When you’re ready to take the shot, fully depress the button
NB: If you move the camera away from your subject, it’ll immediately begin focusing elsewhere, at whatever is in front of the focus point.
Continuous focus is what I use pretty much all the time – perfect for busy little kids and other fast-moving subjects!
Single servo AF for focusing on still subjects
Single servo AF is a good choice if you’re photographing stationary subjects such as:
- Still life
- People that aren’t moving
Again, different brands have different names for it:
- AF-S (Nikon and Sony)
- One Shot AF (Canon)
To use single autofocus mode (AF-S mode):
- Part depress the shutter release button to focus
- The camera will focus and hold that focus, even if you move the camera away
- If you keep holding the shutter release button half way down and recompose your shot by moving your camera, the area you focused on will still be in focus
NB: There’s a danger with this method, particularly when photographing with a shallow depth of field, that your subject might be out of focus when you recompose. Either you or your subject might have moved.
Read about depth of field here: Using depth of field for gorgeous photography composition
How do you change focusing modes?
To change focusing modes, you need to use the autofocus (AF) mode selector button in conjunction with another dial. The exact process will vary from one camera make and model to another. For example:
- On the Nikon D7000, while looking through the viewfinder, select your autofocus mode by holding down the autofocus mode selector button and turning the main command dial to change AF modes
- On the Canon Rebel XS (or 1000D) press the right cross key. Your choices will appear on your LCD screen, then turn the main dial to select your AF mode
But that’s not the end of the autofocus story when deciding on the best way to use autofocus for what you’re photographing.
2. Autofocus area mode decision: Where do I want to focus?
Once you’ve selected which autofocus mode you want to use, you need to decide what part of the photo you want in sharp focus. In other words, which autofocus area mode to use. There are 4 AF area modes to choose from:
- Single point autofocus
- Dynamic area autofocus
- Auto area autofocus
- 3D-tracking autofocus
Let’s look at when and why you’d choose each of these autofocus areas, but first, here’s a handy cheat sheet of autofocus area modes for Nikon and Canon DSLR cameras.
Choosing which autofocus area mode to use
Maybe the reason your photos are sometimes out of focus is because your camera is focusing on the wrong part of the photo? This is where we solve that problem.
You’ll need to refer to your manual to find how to change autofocus area modes on your camera as it varies so much between brands and camera models that I couldn’t cover all of them here.
If you don’t have your camera manual anymore, check out this amazing website – ManualsLib – it has free online manuals on probably everything!
To be a great photographer you need to develop your inner control freak – don’t let the camera decide on what’s important.
Auto area AF
Remember right at the beginning of this tutorial when I said, don’t be tempted to take the easy route? I was talking about auto area autofocus mode.
It’s the default setting on beginner cameras and, in my opinion, the reason so many beginners struggle for so long with nailing focus for sharp photos.
- AF-A (Nikon and Sony)
- AI Focus AF (Canon)
In this mode the camera will automatically choose where to focus, like point and shoot cameras. Because it recognises skin tones, it’ll focus on a person rather than anything else.
If there are many people in shot, it’ll focus on whoever is closest to camera. If it can’t detect any skin tones, it’ll focus on the biggest and closest object in the frame.
The camera switches between single area AF and dynamic area AF automatically. If the camera thinks the subject is still, it chooses single area AF. If the subject moves, it changes to dynamic area AF.
It’s clever stuff, but there’s a lot left to chance. My advice… DO NOT USE THIS AUTOFOCUS AREA MODE! (Okay, that was a bit shouty, but it’s important.)
Further reading: One Shot vs AI Servo vs AI Focus – which AF mode is best?
IMPORTANT TIP 1: I would not recommend using auto-area AF, as how does the camera know what you want to shoot? Even with face detection it won’t always get it right.
Single point AF area mode
With single point autofocus area mode, there’s no question ever about what you want to focus on. The camera is not part of the decision making process.
- Manually select one point for the camera to focus on
- Then move the focus point to where you want to focus
Further reading: Spot metering and single point autofocus – clearing up the confusion
As a portrait photographer, this is my preferred autofocus area mode on a DSLR camera – it puts me in complete control of the shot. I’ll admit though that it can take some getting used to, especially when photographing kids and animals as they never stop moving, which keeps your thumb very busy moving the focus point around!
Further reading on focus: Where to focus in portrait photography to beat fuzzy photos
USEFUL TIP 2: When photographing a person, always focus on the eye nearest to the camera. As viewers, our eyes are drawn to the eye closest to us in an image, so it should be the sharpest point in your photograph.
Dynamic area AF
With Dynamic area autofocus you can choose the number of AF points you’d like to use. Your options depend on your camera make and model. On my Nikon D810, for example, I can choose between 9, 21 and 51 autofocus points.
- Select the dynamic area you’d like to use
- Manually select the main focus point
- The camera then engages the surrounding focus points to temporarily track your subject’s movement and maintain focus
- If the subject moves you can catch up by moving your camera and not lose focus as easily as with single point autofocus
Dynamic area autofocus is helpful for photographing fast moving subjects, such as birds. It’s also great when panning as it gives you a little more wiggle room to lock focus than a single AF point.
Further reading: Panning photography – capturing action with motion blur
3D-tracking (Nikon only)
This autofocus area mode is specific to Nikon and is a great idea in theory, but can be a bit slower to focus than dynamic area. It’s also a bit unreliable, depending on background and what you’re photographing.
- Focus on your subject using a selected focus point and keep the shutter button depressed
- The selected point automatically changes to track the moving subject across all autofocus points, whether you move the camera to follow your subject or not
How to move the focus point
Once you’ve selected the autofocus area mode you want to use, you’ll need to position the focus point on your main subject. Moving the focus point is the same with all autofocus area modes.
To move the focus point on a Nikon:
- Depress the shutter button to see the focus point
- Use the multi-selector dial to move it to your subject
It’s very similar on a Canon:
- Depress the shutter button to see the focus point
- Use the main dial to move it to your subject
The first time you use it might feel a bit cumbersome moving the focus point around if you’re used to using autofocus auto area mode, but you’ll soon get used to it and you won’t look back. Your photos will always be sharp where you want focus to be!
2 further essential points on autofocusing
For the best results using autofocus, these points are key.
- Back button focus
- Staying calm when you click
Let’s take a closer look at why they help with sharp photos.
Back button focus
Once you’ve mastered autofocus mode selection and autofocus area selection, do yourself a favour and learn about back button focusing. Trust me, once you’ve gone back button, you’ll never go back.
With back button autofocusing you can track your subject until the exact moment everything aligns perfectly. At this point you’ll already be focused so you can take the shot without delay.
Using the shutter release button to autofocus delays the moment and can lead to missing the shot because:
- In that split second your subject may have moved out of the area of focus, so your shot won’t be sharp, especially if you’re using a shallow depth of field
- Even worse, your camera might “hunt” for focus at exactly the moment you want to take the shot, causing you to miss it. “Hunting” for focus is when the camera’s autofocus system, in trying to lock focus, works through the full focus range of the camera lens
Back button focusing does reduce battery life, because your camera is continuously focusing. As a wedding photographer I always packed a spare battery so never had a problem, even for all day weddings.
Read about back button focus here: Why back button focus is your BFF, and how to use it
Depressing the shutter button
This may seem like the most obvious thing in the world, but in the heat of the moment we do some strange things. So, I’m hoping that by stating the obvious, you’ll subconsciously be aware of it and won’t:
- Jab your shutter down
- Stab at your shutter button
Just depress the shutter button calmly. No amount of force will make it happen faster.
When you jab or stab at the shutter button, you could also be clenching up your hand and moving the camera slightly at the critical moment. If this happens, all your careful focusing flies out the window and you end up with movement blur in your photograph.
Autofocusing tips for portraits – use a single focus point
Here’s a quick step by step guide to the best autofocus mode for portraits, as well as the best autofocus area mode to use.
- Set your focusing mode to continuous autofocus (AF-C mode)
- Select your autofocus area mode as single point autofocus
- Position your focus point on your subject
- For portrait photography make sure to focus on the eye closest to camera
- Track the selected subject using back button focus until the moment is right to take the shot
- Be cool
- Depress the shutter button calmly
Of course everyone is different, but as a portrait photographer using a DSLR camera, these are my best AF settings for portraits.
Advanced focusing tips for sharp photos
Once you’re comfortable with autofocusing modes and how to use autofocus area modes, you might want to access the custom settings on your camera for advanced autofocus features. Especially if you photograph subjects that move. Such as:
- Sports where individuals are in frame, such as dancers, divers and skiers
- Sports with teams of two, such as skaters and dancers
- Individuals in sports competing against several others in frame, such as runners and cyclists
- Team sports, such as football, rugby and hockey
Further reading: Focus tips to capture moving objects in photography
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