D7200 viewfinder "3D"

Discussion in 'Nikon' started by evilsivan, Dec 22, 2015.

  1. Hi guys
    I am renting a d7200 and occasionally the autofocus points in the viewfinder spell out "3D" I can't figure out why and the body didn't ship
    with a manual. Searching google didn't help. Anyone know what's up?
     
  2. ShunCheung

    ShunCheung Administrator

    You can download the D7200 manual here:
    http://downloadcenter.nikonimglib.com/en/products/197/D7200.html
    I think that is AF with 3D tracking, a feature I don't use myself. See page 87 in the American English manual.
     
  3. Thanks Shun, I couldn't find anything that describes what I saw.
     
  4. I don't think the manual says anything, but this is the same on the D7100. If you have chosen 3D mode, when you press the front AF button, "3D' will illuminate on the screen. In Dynamic Area mode, the chosen AF areas will show. When the button is released, all you'll see is the starting focus point.
    You can get the full instructions on how to select modes from Shun's page reference and those following. Use the button and the front wheel to select between Single Point, 3D, Auto Area, and the various Dynamic Area settings. Use the button and the back wheel to select between AFA, AFC and AFS.
    I don't know why there is no mention of this in the instructions, except to hope that the people who make the cameras are more on the ball than the writers. The d3200 instructions are worse.
     
  5. I don't understand why anyone would let a camera decide on an AF point for itself, and what's "3D AF" anyway? Can it bend the rules of optics to provide more than one plane of focus?
    Think I'll stick with single centre AF point focus under my own control, and hope to never see that dreaded 3D spelled out in my D7200 viewfinder.
     
  6. The D7100 has this too. It's excellent for sporting events. I used it to track my niece during her ice skating event and it keeps track predicatively. It works surprisingly well.
     
  7. Rodeo Joe, 3D focus is not like "auto area" focus, which does indeed let the camera choose a focus point, and in my experience often the wrong one. 3D focus uses a single starting point, just as dynamic area focus does, but differs in the way it tracks motion. In 3D, color and other computed information is used to identify the initial subject, and (in theory at least) it can then track a moving subject with less guesswork, even if it is jumping about. If you switch to 3D you'll see that the chosen point illuminates, but it's often jittery, as the camera's processor is constantly trying to guess where to go next.
    I have yet to find it very useful, but I'm told it's very good if the subject is distinquishable from the background. My lowly D3200 seems to work best in Dynamic Area mode, and my limited experimenting with chasing bugs in the wild suggests that it tends to lose subjects in 3D, but it would not surprise me very much if the D7xxx does it better!
     
  8. Another option is to download Nikon's app called Manual Viewer onto your phone. Into that you can store manuals for all your camera and flashes and have them with you in digital format regardless of your phone platform. Having had it with me has helped several times when I've gotten stuck.

    Tom
     
  9. Matthew, thanks for that explanation. "Focus-tracking" would have been a much simpler and more self-explanatory title for this focus mode, don't you think? But then Nikon's software engineers wouldn't have been able to spell that out in the viewfinder. Well, not without a scrolling display.
    I've got to an age where I'm really not interested in more gadgetry and "features" on a camera. And I personally think that development engineers should concentrate on making the more basic stuff work better. Like an AF system that didn't require hours spent on fine-tuning. There's not much use in tracking a subject if that tracking is always slightly off-focus.
     
  10. ShunCheung

    ShunCheung Administrator

    Like an AF system that didn't require hours spent on fine-tuning.​
    Take a look at this thread from last year: AF Fine tune - is it necessary?
    In particular, Ellis Vener's post as well as my first post on that thread.
    There are two ways to avoid AF fine tune:
    1. You can make all camera bodies and lenses with much tighter tolerance and much more robust so that they don't go out of spec with professional rough usage. The end result is much heavier and bulkier as well as far more expensive equipment.
    2. Go back to 6MP, 10MP cameras that are not as demanding on equipment and precision.
    Clearly neither approach is feasible. I never felt AF fine tune was all that necessary until I started getting 24MP and 36MP DSLRs. While I think most people don't need more than 10MP, such a low pixel count is not going to sell any more.
    But AF fine tune is really not all that difficult. Why resist it?
    Concerning 3D focus tracking, I can see it is very useful for birds in flight, especially when there is a busy background. I have plenty of flight images where the AF system locks onto the background instead. At least in theory, an AF system that can track and automatically pick the subject that is closest to the camera can be great.
    On older DSLRs such as the D300, that option didn't work as well for me, but maybe it is time to give the D7200 another try.
     
  11. Rodeo Joe, the reason why they don't call it just "focus tracking" may be because dynamic area focus is also focus tracking. The difference is in how it does so.
     
  12. I find the 3d and the dynamic area both easy to use and I don't feel like I don't have control. I have never used auto area af as I would also like to not lose control.

    I find it hard to keep track of nikon af types but they do work well.

    In 3d mode it does jump around but that is because I am using a long focal length and my hand is not that steady.
     
  13. I tried the 3D mode out of curiosity and wasn't that impressed. I focused on a white object against a dark background and then moved the camera slowly around. It lost track of the target and locked onto something else almost immediately, and did that repeatedly over several attempts. As well as jittering and jumping between AF areas. I'll give it another go with a moving subject for real, but it's not looking too useful so far.
    Incidentally I couldn't get the D7200 to spell out "3D" in the viewfinder, only on the top LCD.
     
  14. ShunCheung

    ShunCheung Administrator

    Rodeo Joe, while holding down the AF selection button on the D7200 (just below the lens release button), rotate the main command dial to AF-C or AF-A. Now look thru the viewfinder and rotate the sub-command dial to cycle through S, 9, 21, 51 AF points, 3D and Atuo (still holding down the AF selection button), you should see 3D on the lower right hand corner inside the viewfiner at where the frame counter usually is. Additionally, at the same time those 51 AF point would spell out 3D. It is kind of clever. Make sure you don't let go the AF selection button the entire time, though.
    Back in early 2008, I tried out the then new D300 at a tennis tournament. I was in the bleachers from very high up. The tennis court was a US hard count with a green surface. The tennis player was wearing a red shirt, very distinct from the green background. 3D color tracking was able to track the tennis player for a few seconds but would soon lose track of him and jumped all over the place.
    I tried 3D tracking on the D7200 briefly yesterday and didn't feel that it has improved that much from what is on the D300 8 years ago. Perhaps on some subjects it can work really well, especially when the subject occupies a larger portion of the frame, such as ice skating Rich Simmons mentioned above.
     
  15. The D7200 has a relatively low resolution (2016-pixel) RGB meter which is probably why the subject identification and
    tracking (or 3D focus tracking) may not work as well as that in e.g. the D750 (with 91000 pixel RGB meter). Also I think this is why the Group AF
    isn't included. I've found the subject id and tracking to work quite well on the D810. I don't much care for the term 3D that Nikon uses but I suppose two dimensions are in the image plane and the third is distance or focus. Or is one of the dimensions colour?
     
  16. Ilkka is that correct 2,016 vs 91,000 rgb pixels?
     
  17. I found those figures on nikon imaging web pages in the specifications for each camera. Does the information conflict with
    another source? I suppose it is possible that the numbers indicate the total pixel count, divided between R G and B pixels instead of as many of each.
     
  18. I must have gotten lucky with my D300 using focus tracking. Black dog on snow coming towards me, I got a lot of sharp pictures. Not so much with my D7000. The 3D mode is not as good as the D300 focus tracking so I pretty much don't bother with it and just go with AF C. Do either the 7100 or 7200 improve on focus tracking? Is the 7100 noticeably better than the 7000, enough to justify an upgrade, as prices are getting lower?
     
  19. ShunCheung

    ShunCheung Administrator

    From the D3, D300 to the latest D4S, D810, D750, and D7200, the Multi-CAM 3500 AF module still has 51 AF points. All the color matrix metering module needs to do is to identify which one of the 51 AF points the subject falls onto so that AF will focus on that point. A couple thousand color points should be more than sufficient for AF tracking.
    I also tried 3D tracking on the D750 briefly, and I don't find it all that good either. Similar to the D300, it can track the subject for a few seconds and then once it loses track of it, the AF point jumps all over the place. Perhaps I need to try it on many different subjects with different contrasts/colors from the background to fully appreciate when this feature works and doesn't work.
     

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