Nikon AF-area Mode: Single-point AF vs. Dynamic-area AF

Discussion in 'Nikon' started by sinisa_popovic|1, May 28, 2021.

  1. I'm using Nikon D5600 and I don't understand what's the difference between Single-point AF vs. Dynamic-area AF. On my camera you can choose Dynamic-area with 9 points, 21 points or 39 points.
    However they all look and work the same as when you select Single-point AF. I was testing it on many different subjects but they all seem to be the same as single-point AF.
    What's your experience? Do you see any difference if you use dynamic-area focus?
     
  2. Supposedly, dynamic starts with the center AF point. Then will try to maintain focus on the subject as it moves out of the center AF point, limited by the size of the D-area you choose.
    D9 is a 3x3 matrix. I use this one.
    I suspect D21 is 3V x 7H, as that is the only math that works.
    Similarly for D39, the math only works for 3 x 13.​
     
  3. In single point, focus will continue to adjust as long as the object focused on stays in that point. If the subject is coming toward you or you are panning it is fine. If the subject leaves that area it will focus on whatever is now in the area. Dynamic focus basically just increases rhe area in which focus stays on the subject rather than jumping to something else.

    Recommendations I have seen usually suggest the smallest area that works, since larger dynamic areas may allow the focus to move to the wrong part of a subject - for example shifting from the eye to the nearer wingtip of a bird in flight.
     
  4. One thing, Dynamic-area-AF is different than zone focus, as on a Canon T7i.
    • On a Canon T7i, zone focus uses "closest subject" logic. That means the camera will focus on the closest subject/object in the focus zone/area. So for example, in a group of people, the Canon will focus on the CLOSEST person in the group.
    • On the Nikon dynamic-AF, I can put the AF area on whomever I want to, even if that person is NOT the closest person in the group, and it will focus on that person. So it starts off like single point AF.
    Agree with @Matthew Currie, with any of these dynamic, tracking, area/zone focus, you do not have any control over what the camera decides to focus on.
    On my Olympus, I have watched the green AF square jumping around to different spots on my subject.
    So, if you want to put something in focus, you need to focus on THAT SPOT.
     
    q.g._de_bakker likes this.
  5. I have never seen focus jumps on another focus point. It always stays on the one that started focusing with. That's why I said I don't see any difference between single point and dynamic area. I'm using AF-C and back button focus.
     
  6. I do not have the D5600 but use a D810, D850 and D500.
    If your subject is moving around, like a bird on a nest, or a bird in flight or any subject in motion, it is very difficult to keep accurate focus using S (AF-S or AF-C). With S selected focus often shifts to a background subject, like trees, or foreground subjects like tree branches or grass. Using one of the Dynamic settings like D9 or D 25 in AF-C helps to keep focus locked on.

    If your subject is still or static, , then S and the Dynamic area choices, may give you the same, or almost the same, results.

    There are all sorts of videos that show and explain all of this. Here is one. All of Steve's ebooks are worth the $.



    This article might help you:


    Autofocus Modes Explained
     
    bgelfand likes this.
  7. I think with Nikon dynamic AF, you will not see if the camera has selected one of the other focus points within the zone.
    I do not recall ever seeing the AF point move, while in D9.

    But I think I did remember seeing it jump around with 3D tracking.
    I only used Nikon 3D tracking once, to shoot tennis. But when I saw it sometimes selecting the lines on the tennis court, I gave up on it, as not usable for what I shoot.
    I shoot sports, so the color tracking logic will fail. Because everyone on a team is wearing the same color uniform.
     
  8. Don't forget that the Dynamic matrix box isn't locked to the centre of the whole AF area, ie the 3x3 (D9) box could be put in the top half of the frame in portrait orientation.

    The Centre AF point is the one at the centre of the matrix area chosen, not necessarily the one in the centre of the screen.
     
  9. Dynamic area works approximately like this: it focuses using the selected (single) point if possible. If the subject leaves the selected point for a short time and the area under the selected point is clearly out of focus (if there is detail it is far out of focus), it tries to use the surrounding points (you basically set the size of the circle within which the points are included in the dynamic area) to focus. If possible it focuses using those points, but if the primary point (the one that the user selected) sees some contrasty detail that is focusable again, it returns to focusing using that point. What it is good for is moving subjects where the subject is hard to hold on a single point and so you get a short "grace" period where the subject can slip from under the primary point before it focuses on the background or foreground object that may be far away from current point. But after the grace period is up and if you still have not returned the primary point on the subject, it will try to focus on the primary point even if there is just background there.

    You should use dynamic area like it were single point. Try to keep the main subject under the primary point. The camera will help using the additional points for brief moments only. The rationale behind this system is that only the photographer knows where they want the focus but because it is difficult to hold a single point all the time on the correct position of the subject, the camera provides some assistance using the assisting points with the assumption that if the photographer lets the primary point linger in the wrong place (ie. background texture), the camera will have to assume that's the new subject and focus on that.

    This is how dynamic area works on D850/D5/D6. On earlier cameras there were subtle variations on how the algorithm worked - these are not documented in the manual unfortunately, but e.g., some earlier cameras did not focus on background even if the primary point stayed outside of the subject indefinitely as long as the subject remained within the dynamic area. But the problem with that was that if the camera focused on a closer area of the subject using the dynamic area than the subject's eye, the photographer could not easily return the focus to the eye just by returning the primary point on the eye.

    Anyway, I don't have experience with the D5600 so I don't know which variation of dynamic area is implemented in it. But in any case it should not be assumed that the dynamic area algorithm tracks the subject within the dynamic area; the idea is that the photographer always tries to position the primary point on the subject and the size of the dynamic area selected is to tell the camera how large the uncertainty of subject position is in the frame during the action.
     
    Erik-Christensen and Gary Naka like this.
  10. Are any Nikon AF settings designed for closest point?
     
  11. Yes, group-area AF in those cameras that support it normally focuses on closest focusable subject within the area. It's a good choice for distant subjects as it basically never focuses on the background as long as pointed in an approximately correct direction where there is a subject. Also it works great in low light action situations. But subjects that are large in the frame dynamic area gives the user more control.

    I am not quite up to date on this but group area is available on the D7500, D750, D810, D4S, D5, D500, D850, D780 and D6. the D6 also has custom group area which allows one to adjust how many rows and columns are included in the group area, and you can select facial recognition so it focuses on the closest face instead of closest subject area under a focus point in the area. On some other cameras the standard group area can prioritise faces when in single-shot focusing mode.

    In cameras without group area, auto area may work for some cases and prioritises closest subjects over the background (though it is a little hard to figure out what it does). I have read that some bird in flight photographers use auto area AF. I just felt it gives a little bit too much control to the camera and less on the photographer so I haven't used it much.

    My most common focus area modes are 9-point dynamic area and single point.
     
    Last edited: May 29, 2021
  12. If you use "Auto" exposure mode, the camera is in "closest subject AF mode."
    This is why I NEVER use Auto.
    The camera focused very well on the dinner table in front of my guests, not my guests on the other side of the table.
     
    mike_halliwell likes this.
  13. +1 for Joseph_Smith's recommendation of the Steve Perry video. It is a very good explanation of Nikon Auto Focus. Although it uses wildlife subjects, the principles apply to all subjects.
     
    luis triguez likes this.
  14. Camera manufacturers have gone out of their way to make AF as powerful and confusing as possible. Manuals tell you what options do, but not when to use them. Making those judgements takes practice, and different cameras behave differently.

    In general, wide area focusing will lock on the nearest object. It's good for snapshots or when the subject(s) are in a single plane, as long as there's nothing in front of them. The Nikon Z's have face and eye recognition, which used in conjunction with wide area focusing may constitute the mode you use most often. I would include area focusing, are subsets of wide area patterns.

    Single area focusing has the most options, but gives you the precision many photographers prefer, when not pressed for time. A single spot can be fixed, or moved off center using a joystick or 4-way. An expanding spot option uses that spot as the aiming point, but will expand the area to find the best object near that spot. "Best" is subject to interpretation - which you can only learn by experience. Tracking is the most powerful and interesting. Once you lock the spot on an object, it will stay on that object if it moves or you move the camera. A Z camera has hundreds of focusing points covering over 90% of the image area, lending much more power to tracking than that of a DSLR. Furthermore the blackout time is much shorter for a mirrorless camera.

    My rule of thumb is wide area for groups and snaps, spot with focus lock for landscapes and closeups, and tracking for action or focus-and-recompose use. The next job may make me change my strategy. And so it goes.
     
  15. Auto area AF has its place; I've used it successfully for figure skating for pairs and ice dancers and it allows the photographer to concentrate on the action and composition and while the outcome is not as precise as with narrower focus areas, it doesn't focus on the background which in this context is a good thing. It is also reported to work well for birds in flight.

    But it's not really an all-purpose auto setting where one can just forget about focusing like its name might be interpreted to suggest.

     
  16. I may have missed it, but in answer to the question above, in dynamic area mode the focus point does not move, so there is no visual cue to where in the area it is. It does move in 3d.
     
  17. Nikon changed the behavior of indicated focus point for dynamic area at some point. In recent cameras the selected primary point is always displayed e.g. in Nikon ViewNX-i/NX studio. In the past the point shown would indicate which point the camera actually used to focus, not necessarily the center point.

    In the D6 files, also the 3D tracking point shown is shown differently - it shows multiple points as being used to track the subject whereas in earlier cameras it is a single point being shown.
     

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