Af options: which autofocus mode to choose? Af-s, af-c

Cameras offer various Autofocus options. Is not at all easy to tell them apart. What are AF-S and AF-C? Which autofocus mode is the right one for which motive?

What is an autofocus mode?

Autofocus modes refer to the way in which your Autofocus at Focus on a subject behaves.

To begin with, it is important to understand how autofocus works in general:

First, press the shutter button halfway down. This sends a signal to your camera to start focusing. Then you press the shutter button all the way down. Your camera triggers a (hopefully focused) shot.

Autofocus Racing AF-C

Autofocus mode tells the camera what to do when you press the shutter button halfway down. In other words:

Should the camera find the focus as quickly as possible and then stop focusing?
Or should the camera find focus, but then continue to focus when the subject changes?

This is what autofocus mode is all about.

By the way, there is another important mode: Manual focus. It is technically not an autofocus mode and therefore will not be covered in this article. But manual focus is an important technique to be familiar with. Because it can be useful in many situations.

There is no universal Autofocus mode. You have to set the AF mode correctly depending on the subject you are photographing.

What are the common autofocus modes?

If the autofocus modes tell the camera what to do when you press the shutter button halfway, which modes can you choose? And what do they do?

In general, there are two basic AF modes:

AF-S (also known as single frame AF, single AF) and AF-C (also known as focus tracking, continuous AF or servo).

There’s a third autofocus mode, AF-A, also known as automatic focus, but it’s not found on all cameras. It is a fully automatic mode with no possibility of intervention. We will come to this later.

Now let’s look at each AF mode in turn:

AF-S static autofocus mode AF-C

AF-S autofocus mode is often the default mode for photographers because it works in a very simple way:

When you press the shutter button halfway, the focus is locked on the area below your AF point. The focus stays locked until you release the shutter or take a picture.

In other words: When you press the shutter button halfway down and lock focus, this point no longer changes. Not even when you’re focusing on a bird that’s flying away or a car that’s moving.

The focus point is fixed as long as the shutter button remains half pressed!

This is in contrast to AF-C, which I discuss in the next section:

AF-C focus tracking AF-S autofocus mode

AF-C is a more complex autofocus mode. It works by continuously trying to lock focus on the subject as long as you hold down the shutter button.

So as soon as you press the shutter button halfway down, it starts focusing. It can focus on a person, a rock, a wall, whatever. If the subject moves forward or backward under the autofocus point, the camera will change the focus point and follow it. Even if an object comes between the camera and the subject, the focus is readjusted. But this depends on other options that can be set, more about this later.

Note that in AF-C mode your camera can constantly change the focus point to follow a subject. So this is interesting for sports photography, moving animals, car racing and the like.

AF-A is not available on all cameras; it is intended for photographers who are just starting out. It is virtually an automatic system that decides for itself which mode is the right one at any given moment. And that tends to go wrong. It basically switches back and forth between AF-C and AF-S depending on whether your camera detects a moving or still subject.

I personally do not recommend using AF-A. Because you don’t have the same degree of control as with AF-C or AF-S. With AF-A, you never know exactly what will happen when you press the shutter button. This is because the camera may detect whether the subject is moving or stationary, but it is not perfect at doing so.

When should you use the autofocus modes?

As I said above, I do not recommend using AF-A.

But what about AF-S and AF-C? When does it make sense to use these two modes? It’s easy:

If you are shooting still subjects, use AF-S. And for moving subjects use AF-C.

In this way, you can shoot at still subjects use helpful techniques, such as z. B. the focus and recompose, where you focus on your subject and then recompose the image. This is especially interesting in portrait photography and when you focus on an off-center subject.

At moving subjects on the other hand, you can track your subject throughout the frame. The focus is then automatically tracked and the subject remains sharp in any case, even with a race car.

Does this make sense? Now, what I suggested, using AF-S for still subjects and AF-C for moving subjects, won’t always work perfectly.

For example, what if you’re dealing with a subject that’s mostly still, but occasionally moving? Like z. B. A bird foraging for food? For those moments when the bird is stationary, you should use AF-S so that you can lock focus and take a series of shots. In addition, you can recompose and refocus whenever you need to.

However, for those moments when the bird is moving, you should use AF-C to get nice action shots. Of course, you can always switch back and forth between modes, but by then it might already be too late.

Here’s the solution: the AF-ON button.

What is AF-ON autofocus and when should you use it?

AF-ON button with Nikon AF-S AF_C

Autofocus via AF-ON button is an alternative method of focusing with your camera. Instead of focusing by half-pressing the shutter button, it happens with a button instead. It is on the back of the camera (AF-ON button).

Basically, you set your camera to switch the AF trigger from a half-pressed shutter button to AF-ON button.

What makes back-button AF special is that it decouples the focusing mechanism from the shutter release button.

So if you want to focus and track your subject, you can hold down the AF-ON button on the back while taking pictures. But once you want to lock focus (that is, when the subject stops moving), you can simply stop pressing the AF button.

Sharpness is maintained and you can continue shooting with the shutter button on the front side.

For this reason, the AF-ON method is a common way for action, street, and wildlife photographers to focus.

However, this method is only useful to use if in the menu Individual functions “AF activation” specifies that autofocus is not activated when you press the shutter button, but only with the AF-ON button.

What is AF-Lock?

AF Lock is a setting that is offered on many cameras. It allows you to focus normally, but then lock your focus point even when you release the shutter button.

It’s a good way to keep your focus point whether you’re shooting with AF-C or AF-S. But I do not recommend you to use it regularly. It is better to lock focus by half-pressing (and holding) the shutter button or switch to back-button AF.

AF-lock button

What are AF-area modes?

AF point modes are the second main feature of autofocus systems.

Rather than telling autofocus how to behave in the broadest sense, AF point modes determine the distribution of AF points and how they can be used.

What does it mean? Auto focus points are simply points that can lock focus. Points can be active or inactive. So if you have an active autofocus point in the center of the frame and you press the shutter button halfway down, that point will be focused on the subject in that part of the frame.

However, if the center point is inactive, the autofocus system ignores this point completely and uses another (active) point for focusing.

Ideally, every point would be active and the camera would magically know exactly where you want to focus; and which AF points to use. Instead, you need to specify which AF points you want to use. Or at least you have to tell your camera to select the AF points itself, which doesn’t always work well.

That’s what AF point modes are all about:

You specify which points to use and how they should work. Now, different camera systems offer different AF point modes. Thus, there is no uniform range of options as there is with basic autofocus modes. But there are some commonalities, which I’ll explain in the next section.

What are the common AF point modes?

In general, there are three major auto focus area modes that are present on most modern cameras.

These are the AF point modes you should know about, as quickly switching between them can be very useful when taking photos.

Single point

Single field AF mode

Single point AF point mode is a fairly simple option.

You use the camera buttons or joystick to designate an AF point you want to activate. And then your camera will only focus in that area.

Note that this is the most precise of the AF point modes, so I recommend this mode if you can take some time and focus deliberately.

A good strategy is to choose the center AF point, aim it at the part of the photo you want to be sharp, finally half-press the shutter button to lock focus, then recompose and take the shot.

By the way, there are other modes for single-point AF fields; some cameras offer z. B. A mode where you can first specify which point you want to activate. Then, when your subject moves, the surrounding AF points become active and you can continue to focus on the subject.

3D Tracking

AF tracking algorithms are getting better and better, which means tracking AF modes are becoming very popular.

Tracking modes typically let you let your camera identify subjects in the frame (based on many features, including motion). Or you can choose the first focus point. Then your camera will do everything it can to “stick” to the subject. And that’s even when it’s around the viewfinder and even behind objects. For Nikon, by the way, the process is called Lock-On.

AF tracking modes can also include some form of eye AF, where the camera identifies an eye and tracks it through the image. This is very useful for portrait, pet and animal photography.

I recommend using the tracking modes whenever you are faced with moving subjects of any kind. And especially if your camera can handle complex movements. The tracking function is popular with wildlife, bird and sports photographers because it allows you to get sharp shots even when the subject is moving.

It should be noted, however, that AF tracking is not as precise as other focus modes. And that relying on the camera’s tracking algorithms can sometimes lead to missed shots. This is especially true when you’re shooting in difficult situations, z. B. In backlit or low-light conditions.

Auto autofocus

Auto AF point modes work as you would expect them to:

You press the shutter button halfway and your camera decides where to focus. In other words, you have no control over AF points; that’s entirely up to the camera. In situations where you’re not dealing with moving subjects, but don’t have time to focus carefully, auto AF point modes are a good option.

But you can’t predict what you want to focus on, which means that you often focus randomly, which is far from what you wanted to achieve. That’s why I generally recommend using a single-point AF point mode for still subjects and AF tracking for moving subjects.

Autofocus Modes: Conclusion

Now that you’ve finished this article, you should know all about the different autofocus modes, including AF-ON button, AF lock, AF area modes, and more.

And you should be able to select the right focus mode for the right situation. This way you will always get sharp shots!

What are AF point modes?

AF field modes are ways to control the different auto focus points. They allow you to select individual autofocus points or tell the camera to track the subject through different parts of the frame. It’s important to choose the right AF point mode for your shooting situation. Because this way you can maximize the number of sharp shots!

What is AF-C compared to AF-S?

AF-C is a continuous autofocus that constantly focuses while you hold it active. AF-S, on the other hand, is a one-time autofocus, d.h. when you press the shutter button halfway down, focus is locked; only when you release the shutter button can you refocus again.

What is the best autofocus mode?

There really isn’t one best autofocus mode; both AF-S and AF-C are good in different situations. AF-S is great for working with still subjects. AF-C, on the other hand, is perfect for tracking moving subjects in the frame by instructing the AF system to continuously lock focus, even while you’re taking photos.

What is the AF-ON button?

The AF-ON button activates an advanced method of autofocus that decouples the shutter release from the focusing mechanism. Instead, only the AF-ON button on the back of the camera can activate the autofocus of the camera. You just need to press the button on the back and your camera will start focusing. This is useful in situations where you want to focus continuously and then lock focus quickly.

What is AF-Lock / AF-L?

AF-Lock function locks your focus point even when you take your finger off the shutter button.

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