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I am using Nikon D5100. To shoot a subject which is:

  1. Stationary:
    • we can set AF-area mode to Single Point AF
    • we can set Focus mode to AF-S
  2. Moving:
    • we can set AF-area mode to Dynamic-Area AF
    • we can set Focus mode to AF-C
  3. Or we can set both AF-area and Focus mode to Auto-area AF and AF-A

These settings for AF-area mode and Focus mode look similar to me. I am not able to make out a difference between these two. What if the camera only has AF-area mode and no Focus mode?

Please let me know what I am missing here.

Thanks.

Piyush Kansal
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2 Answers2

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Short Answer: Focus mode is how the camera focus while the AF-area is where the camera focus.

Focus modes

  • AF-S/One Shot AF - Find focus only once while the release button is half-pressed
  • AF-C/AI Servo AF - Find focus until the release button is fully pressed or released
  • AF-A/AI Focus AF - Let the camera decide if it should use AF-S or AF-C
  • MF - The photographer decide the focus manually

AF Area

  • Single point - Focus mainly on the selected point
  • Dynamic-Area - Focus on the selected point and the area around it in case of movement
  • Auto-area - Camera decide where it should focus on
  • 3D-tracking - A better tracking of objects in motion. (Not all cameras have this mode)

For a bit more detailed answer on AF Area you could check the answer from the question: When to use a particular auto-focus mode

Community
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Yao Bo Lu
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  • Auto Area AF seems to imply face detection according to Nikon's materials – Imre Jan 27 '14 at 12:04
  • There is no face detection in D5100 in the through-the-lens mode (the OP uses that for focusing). Face detection is only available in LiveView (and I have not yet seen any camera actually that does face detection through the lens). – TFuto Jan 27 '14 at 12:45
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In AF-S, you can use

  • Single-point AF (you select a fixed focus point)
  • Auto-area AF (camera selects focus point automatically)

When focus is acquired, there is no more focus tracking.

In AF-C and AF-A, you have

  • Single-point AF (you select a fixed focus point)
  • Dynamic-area AF (you select a fixed focus point, camera tries to stay in focus by using nearby focusing points as well)
  • 3D-tracking (you select the subject by a focus point, camera tries to track that subject)
  • Auto-area AF (camera selects focus point automatically)

The camera is adjusting focus as the subject or your camera moves.

Note that AF-A can switch to AF-S or AF-C when in Single-point AF or in Auto-area AF!

So the total combinations are:

  • 2 in AF-S
  • 4 in AF-C
  • 4 in AF-A with the flavor that it can select AF-S or AF-C in two modes.

I hope this answer your question.

For more information, see the D5100's User Manual page 32 for TTL focus, page 44 for LiveView focus.

TFuto
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