how to
photograph
wild birds

Lesson 13

Where do I focus? Part 1 (Focusing with single AF point(s))

Autofocus (AF) uses AF points and AF areas to acquire focus. Your camera lets you choose from a number of AF point and AF area patterns, from single points to zones, and mixtures of both. Understanding the different patterns will bring you closer to getting the shots you want.

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Black-tailed Gull
Black-tailed Gull
Black-tailed Gull
Enlarge

I focused on the Black-tailed Gull's eye with Center-Point AF and tried to get a close-up of its face. The photo turned out like this using the factory default setting (One Shot AF mode).

Image data
  • Aperture value: f/10
  • Shutter speed: 1/1600 second
  • ISO speed: ISO400
  • Exposure compensation: 0
  • Focal length: 400mm
  • DSLR Camera (APS-C image format)

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AF points and AF areas

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Cameras are equipped with an array of AF points that the autofocus function uses to focus on the subject. Different camera models have different numbers of AF points.
An AF area is a cluster of AF points within the image area that are used to determine focus. Cameras offer a number of AF area selection modes, ranging from modes using only a single AF point to modes using all of the AF points.

Selecting AF area selection modes

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AF area selection modes can be roughly divided into those that lock on subjects with points and those that lock on with zones. Basic AF area modes focus with one or more AF points and are suited for getting the sharpest focus. Modes that focus with AF points grouped in zones are best for fast moving subjects or subjects whose movements are unpredictable.

This lesson concentrates on point-type AF area selection modes. When you buy a camera, it is set to Single-point AF by default. However, it is very useful to learn to how to use other modes — Spot AF, AF Point Expansion (4 points), and AF Point Expansion (8 points) — to handle various shooting situations.

List of AF area selection modes

AF area selection mode Point / Zone Description
Single-point Spot AF Point This mode has the narrowest AF sampling area selected by the user. Spot AF is effective when the subject is obscured by such objects a cage, a fence or branches.
Single-point AF Point This mode uses a single AF point that is selected by the user and slightly wider than Single-point Spot AF. Single-point AF is effective when the subject is obscured by such objects as a cage, a fence or branches.
AF point expansion Point With this mode, a cluster of five AF points — four secondary AF points surrounding the primary AF point selected by the user — is used to focus. It is effective for capturing subjects that make small, erratic movements.
AF point expansion (Surrounding points) Point With this mode, a cluster of nine AF points — a box of eight secondary AF points surrounding the primary AF point selected by the user — is used to focus. It is effective for capturing erratically moving subjects.
Zone AF Zone This mode uses a group of AF points selected by the user to focus and divides the AF area into nine zones. Zone AF is effective for capturing fast-moving birds while you pay attention to the overall composition.
Large Zone AF Zone This mode uses a large group of AF points selected by the user to focus and divides the AF area into three zones — left, center, and right. It is effective for capturing birds moving erratically that the camera would have trouble tracking with Zone AF.
Automatic selection AF Entire AF area This mode focuses using all AF points (the entire AF array). It is effective for birds moving very vigorously or whose movements are unpredictable. Different camera models have different numbers of AF points.

AF area selection mode

Single-point Spot AF

Point / Zone: Point

This mode has the narrowest AF sampling area selected by the user. Spot AF is effective when the subject is obscured by such objects a cage, a fence or branches.

Single-point AF

Point / Zone: Point

This mode uses a single AF point that is selected by the user and slightly wider than Single-point Spot AF. Single-point AF is effective when the subject is obscured by such objects as a cage, a fence or branches.

AF point expansion

Point / Zone: Point

With this mode, a cluster of five AF points — four secondary AF points surrounding the primary AF point selected by the user — is used to focus. It is effective for capturing subjects that make small, erratic movements.

AF point expansion (Surrounding points)

Point / Zone: Point

With this mode, a cluster of nine AF points — a box of eight secondary AF points surrounding the primary AF point selected by the user — is used to focus. It is effective for capturing erratically moving subjects.

Zone AF

Point / Zone: Zone

This mode uses a group of AF points selected by the user to focus and divides the AF area into nine zones. Zone AF is effective for capturing fast-moving birds while you pay attention to the overall composition.

Large Zone AF

Point / Zone: Zone

This mode uses a large group of AF points selected by the user to focus and divides the AF area into three zones — left, center, and right. It is effective for capturing birds moving erratically that the camera would have trouble tracking with Zone AF.

Automatic selection AF

Point / Zone: Entire AF area

This mode focuses using all AF points (the entire AF array). It is effective for birds moving very vigorously or whose movements are unpredictable. Different camera models have different numbers of AF points.

Note: Not all camera models feature every mode listed above. Furthermore, certain lenses may limit the number of AF points available.

Selecting modes

1 Press the AF Point Select button on the rear of the camera or the AF Area Select button on the top. Each press of the AF Area Select button cycles through the AF area options.

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Viewfinder display

2 Select the primary AF point or the AF zone with the top and rear dials.

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Viewfinder display

3 Half-press the shutter button to set the AF point or AF zone.

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Single-point Spot AF (Manual selection)

I wanted a scenic composition with the Kobushi magnolia flowers in the frame, instead of a close-up of the Ezo Ural Owl. I found the surrounding branches got in the way of the Ezo Ural Owl, which was small in the frame, so I used Spot AF to focus precisely on the owl (One Shot AF mode).

  • Aperture value: f/5
  • Shutter speed: 1/2500 second
  • ISO speed: ISO200
  • Exposure compensation: -0.3
  • Focal length: 100 mm
  • DSLR camera (APS-C image format)
Image
An Ezo Ural Owl in a forest
An Ezo Ural Owl in a forest
An Ezo Ural Owl in a forest
Enlarge

AF point expansion (4 points) (Manual selection)

A Water Rail was popping in and out of a thicket (AI Servo AF mode). Because it was feeding, the bird's pace and movements were all over the place. I would often lose focus using a single AF point, so I switched to four-point AF point expansion (Manual selection), which kept the camera from losing focus since the neighboring AF points assist in focusing. If I had used a zone-type AF mode, the surrounding branches would get in the way and make it harder to keep the bird in focus.

  • Aperture value: f/5.6
  • Shutter speed: 1/800 second
  • ISO speed: ISO400
  • Exposure compensation: -0.7
  • Focal length: 500 mm
  • DSLR camera (APS-C image format)
Image
A Water Rail in a thicket
A Water Rail in a thicket
A Water Rail in a thicket
Enlarge

AF point expansion (8 points) (Manual selection, surrounding points)

A Pacific Golden Plover repeatedly stopped and started moving as it fed (AI Servo AF mode). It was tough to keep the AF point on the bird even with four-point AF point expansion (Manual selection). The wider assist cluster of the eight-point AF point expansion (Manual selection, surrounding points) mode comes in handy in situations like this.

  • Aperture value: f/5.6
  • Shutter speed: 1/2000 second
  • ISO speed: ISO400
  • Exposure compensation: 0
  • Focal length: 700 mm equivalent
    (used a 1.4x extender at 500 mm)
  • DSLR camera (APS-C image format)
Image
A feeding Pacific Golden Plover
A feeding Pacific Golden Plover
A feeding Pacific Golden Plover
Enlarge

Comment from a learner

When I first attempted to shoot the Little Egrets in the background, all I got were the weeds in the foreground. I tried again, switching the AF area selection mode to Single-point AF as Mr. Tozuka taught me. I thought it was going to be hard to focus on a subject surrounded by so many obstacles, so I was really surprised I was able to cleanly capture the Little Egrets just by setting the camera to Single-point AF.

  • Camera settings
    AF operation: One Shot AF
    AF area selection: Automatic selection AF

    Image
    Little Egrets, by a learner (Failure)
    Little Egrets, by a learner (Failure)
    Little Egrets, by a learner (Failure)
    Enlarge

    Aperture value:
    f/6.3
    Shutter speed:
    1/320 second
    ISO speed:
    ISO160
    Exposure compensation:
    0
    Focal length:
    350 mm
    DSLR camera (APS-C image format)

  • Camera settings
    AF operation: One Shot AF
    AF area selection: Single-point AF (center point)

    Image
    Little Egrets, by a learner
    Little Egrets, by a learner
    Little Egrets, by a learner
    Enlarge

    Aperture value:
    f/5.6
    Shutter speed:
    1/250 second
    ISO speed:
    ISO160
    Exposure compensation:
    0
    Focal length:
    350 mm
    DSLR camera (APS-C image format)

Message from Mr. Tozuka

In the first photo, since the camera was set to Automatic AF point selection, the focus unfortunately locked on the foreground grass instead of the Little Egrets. Using Single-point AF, the autofocus ignored the foreground grass and avoided focusing beyond the background reeds. Instead, the camera captured the Little Egrets in crisp focus.