Focus on Autofocus

Focus on autofocus is the best tip I can give you so that your photos don’t come out shaky, blurry and strange. Why focus on Autofocus? Well, it’s very simple. Today 90% of photographers are dependent on their cameras’ autofocus system. Only in very special cases is it possible to spot someone using only manual focus, without depending on the technology. 

And in the next lines you will see what and how it all works together so that your photos are always sharp!

Focus on Autofocus

First of all. Manual focus vs Autofocus.

In manual focus you are the solely responsible for acquiring focus on the photos, you can count on more than one way to achieve this. You can manipulate the lens of your camera, you can approach or move away from what you are photographing, just like moving the object to be photographed.

In short you are in control, and often these are the only tools you have at hand to take a good photo. So never underestimate manual focus. But as the conversation today is about auto focus, or AF, and how it works and also the various types of autofocus modes available.

The focusing systems of modern cameras are extremely complex and often new cameras are launched only because of a new focusing system. To reduce the massive part of this text we go straight to what really matters.

Autofocus types

Phase detection

Phase detection is more common in DSLRs and employs what is known as a beam splitter. This beam splitter directs the light (the image) to two different micro sensors, thus creating two separate and identical images.

These are aligned (focused) automatically using the camera’s internal software. The better the camera’s internal software and focus sensors, the better and faster the focus acquisition process will be.

Foco no Autofoco

If you’ve ever used an old film camera with manual focus lenses, you can remember how the image or scene would appear divided in the center of the viewfinder, and focus was achieved by aligning the two misaligned images. Phase detection works this way.

Contrast Detection

Contrast detection is possibly more accurate than phase detection, especially when photographing objects (portraits) in close-up with a wide aperture (f / 1.4-f / 2.8).

Foco no Autofoco

Contrast detection is a more modern technology present in smaller cameras and mirrorless cameras, in addition to smartphone.

As it is a less complicated and cheaper technology, it is common to see the growth of this type of focus detection increasingly present in our cameras. The contrast detection autofocus is obtained by measuring the contrast in the camera’s image sensor.

The difference in intensity between the adjacent pixels of the sensor naturally increases with the correct focus of the image. The optical system can thus be adjusted until the maximum contrast is detected.

In this method of autofocus does not involve measuring actual distance and this creates significant challenges when tracking moving subjects, since loss of contrast does not indicate the direction of movement. So here is a tip, depending on what you shoot it is interesting to choose a camera with a specific type of focus.

If you are shooting sports for example, phase detection will be a great advantage for you because it is much more robust and responsive than contrast detection.

Foco no Autofoco

There is nothing more frustrating than getting home and seeing that you get almost everything in the photo right but it is out of focus.

So if you want your photos to reach a higher level of focus, read this post to the end, and you won’t be sorry. In addition to the types of focus, phase or contrast, we have hybrid focusing systems that use this two combined systems to acquire focus.

Focus Modes for Nikon and Canon

Auto Focus (AF-A) Nikon | AI Focus AF Canon

In Auto Autofocus (AF-A), the camera analyzes the scene and determines which AF point / points to use. Based on whether the object is moving or stationary, it automatically switches between AF-S and AF-C to achieve focus.

O atributo alt desta imagem está vazio. O nome do arquivo é uc
O atributo alt desta imagem está vazio. O nome do arquivo é uc

Single Servo AF (AF-S) Nikon | Canon One-shot AF

In single-servo AF (AF-S), the selected AF point is attached to the subject to be photographed as long as the shutter-release button remains partially pressed.

The focus lock is usually indicated on the viewfinder by illuminating a solid green circle on Nikon cameras. When the focus is acquired and locked, the scene can be recomposed without losing focus on what is being photographed. This AF mode is ideal for subjects that are stationary.

O atributo alt desta imagem está vazio. O nome do arquivo é uc
O atributo alt desta imagem está vazio. O nome do arquivo é uc

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Continuous Servo AF (AF-C) Nikon | AI Servo Canon AF

In Continuous Servo AF (AF-C) focus, the camera continues to adjust the focus at the selected AF point until the shutter is activated. This AF mode is ideal for moving subjects.

O atributo alt desta imagem está vazio. O nome do arquivo é uc
O atributo alt desta imagem está vazio. O nome do arquivo é uc

The AF area mode or autofocus points

In addition to these focus modes, Nikon and Canon DSLRs come equipped with various AF point configurations. These modes may vary in quantity and behavior, depending on your camera model.

Pés de um bebe

Nikon AF Area Modes

Nikon allows you to choose the following AF area mode options:

Single point – The photographer determines a single AF point manually and the camera focuses on the subject in that region.

Tipos de ponto de foco Nikon

Dynamic Area – The photographer determines the AF point manually, as with the Single AF Point.

Seleção de pontos de foco Nikon

However, if the subject moves and leaves the selected AF point area, the camera adjusts according to the surrounding AF points and refocus accordingly. This setting works best with subjects that are moving unpredictably.

Auto – The camera determines which AF point contains the subject and focuses automatically, without the photographer’s intervention.

Sistema de autofo Nikon

3D – The photographer determines the AF point manually. When the shutter-release button is pressed halfway and the camera reaches focus.

Menu de autofoco Nikon

The photographer can recompose the scene, but the camera will automatically switch to a new AF point to maintain focus on the selected subject.

Canon’s AF Area Modes

Canon’s AF area mode options are very similar to those of Nikon, but are most affected by AF point groupings to achieve focus.

AF Point Expansion – This mode allows you to select a main AF point, accompanied by 4 or 8 additional AF points. Very important mode for photographing subjects in motion or that do not offer a lot of contrast for the acquisition of focus.

Zone AF – Provides a group of 9 or 12 groupings of moving AF points to focus on the closest subject that fits the selected zone.

Auto AF Point Selection – In this mode, all AF points are active and the focus is very similar to Nikon’s 3D AF mode.

Don’t just rely on the text on this blog or your camera manual, the best way to see it all in practice is to go out and test each one. The next subject is something that many photographers, even some who claim to be professionals, have no idea what can be done, and this will make an incredible difference in the focus of your photos.

Lens calibration

Correct lens calibration is also critical to obtain optimal results with DSLRs and lens combinations – fixed and zooms. Lens calibration is the first step you must take to achieve consistency and precision in focus.

Calm, this can be done directly on your camera, once calibrated that lens tends to work well with that body. Nikon offers fine-tuning AF on some of the latest cameras and this is a valuable tool. Canon cameras can also do this.

In the video above you can see how the whole process can be done and how simple it is to properly pair a lens with a body. Once your lenses are calibrated they tend not to “lie” the focus, but none of this will help you if don’t know how to use everything the camera offers.

The AF-S mode, or equivalent, is usually the simplest and most consistent for those who acquire focus faster. The advantage of being able to recompose the scene without losing focus makes your composition options much more varied.

Closeup de um gato - foco no olho

Focusing on moving subjects

Cavalhos correndo - autofoco no movimento

Whenever you shoot something that is moving, a good combination of settings is AF-C + Dynamic Area AF on Nikon.

If you use Canon can AI Servo AF Canon + Zone AF, usually these combinations are the ones that work best in these situations. The consistency of focus between several photos is what makes me suggest these settings, but feel free to try other combinations.

Remember, Dynamic AF and Zone modes allow you to select groupings of AF points that range from groups of 4-8 points to maintain constant focus tracking for moving subjects.

When I am a little further from moving subjects, I have found that shooting in Continuous-Servo AF (AF-C) in combination with 3D area AF (Nikon) or Auto AF (Canon) produces the most consistent results.

Focus on portraits

I think the most significant focus challenges come with capturing portraits or close-up details with longer lenses (50 mm or more) at f / 1.2 – f / 2.8 apertures.

This is where professionals separate from amateurs.

Many photographers want to achieve the striking visual effect (bokeh) with a blurred background that we see when shooting a wide-open subject (f / 1.2 – f / 2.8). But few realize that this can be a little more complicated work than just using a fast lens, or any of the ghastly cell phone apps.

And for this it is necessary to understand a little about and depth of field, and I’m already saying that it may not be an easy subject for everyone. Whenever we use very wide apertures, we decrease the effective range of acceptable focus in a portrait.

So when we are photographing a half-profile face for example, it is possible to put one of the model’s eyes in focus and easily lose the eye furthest away from the lens, due to the aperture. These small details often cause you to focus on the wrong eye or lose focus entirely on the important area in the portrait.

The big trick here is to mix everything you’ve learned and test different combinations and settings for each situation.

Menina olhando para o horizonto - autofoco nos olhos

Conclusion

Autofocus is a powerful and convenient tool that has helped to evolve and elevate photography over the past 20 years. However, with all mechanical and human things, there are weaknesses and limitations. Furthermore, there are no limitations when it comes to imagination or creative desires.

As the autofocus technology is constantly evolving it is something that we will still talk about and use for a long time. It is worth every penny to get your camera and go out and try the types of focusing in the most varied situations, only then will you be able to define what is best for you.

Leave your comment with what you think about the article, and if you have any other tip please share with the community. CYA!

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