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I am recently trying to experiment with types of photography that I have not done much before before. One of these is photographing subjects that are moving towards or away from me. But I have experimented with all the different focus modes (AF-S, AF-C, AF-A as well as single-point AF, Dynamic-area AF, 3D tracking, and auto-area AF). But I am unable to take the shot when the subject is moving towards me. What I see happen in every possible mode combination is that when I press the shutter it instead stops focusing and refuses to take the picture at all and then the subject just goes out of focus! I have tried pressing the shutter halfway and hold it so that it will automatically continue focusing, and I have tried letting off the shutting and only pressing down when I am ready to take the picture. In the latter case if I am really quick I can get off a single shot if I am lucky, but I am in continuous release mode and it does not continue to track focus and fire more than one shot.

If the subject is moving slow enough relative to my zoom setting that they are not moving out of focus very fast then I do not see this issue. I need a lot of zoom to bring the subject close enough, but there is plenty of light (for example, 1/1000s, f6.3, iso 220, 270mm zoom) But I do not have any control over how fast the subject is moving, so it's more blind luck and I wind up missing shots I feel like my camera should have taken.

This is a Nikon D5100 (as given by the tag) with a Tamron 18-270mm f/3.5-6.3 lens.

Am I doing something wrong? Is this an issue with my camera? The lens? It's really old (9 years) but I feel like it has always had trouble focusing on fast moving scenes, it's just that I rarely did such photography before. But I have always noticed that in for instance AF-C the lens does this little periodic click clack at times when continuously focusing, so maybe this model is just not good at this?

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    "Is this an issue with my camera? The lens?" – This is unanswerable without knowing what camera and lens you are using. However, AF is an active area of development. New models continue to improve AF performance.
    – xiota
    May 19, 2020 at 2:04
  • @MichaelC I have updated the question with this info, although the model was already in the tag.
    – Michael
    May 19, 2020 at 4:39

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In order to even have hope of tracking moving subjects, you need to be in AF-C mode. If you are in AF-S mode, the camera will not even attempt to follow a subject as it moves closer or further from your camera.

If you can hold a single AF point on the subject, use single point AF. Otherwise use 3D tracking and be sure the initial AF point is on the subject when you initiate AF.

You're being affected by at least two issues related to your lens choice:

  • Your lens uses Tamron's PZD AF technology
  • Your lens' "slow" maximum aperture makes it harder for your camera's AF system to work well.

Your lens is a 2010 design from Tamron that uses their PZD (piezoelectric drive) AF motor. This technology wasn't used in very many Tamron lens models, and there's probably a reason for that. The few lenses that used it were all low cost budget models. Apparently the last lens introduced with a PZD AF motor was 2014's 28-300mm F/3.5-6.3 Di VC PZD. Higher priced and more recent Tamron lenses use USD (Ultrasonic Drive) AF.

One of the disadvantages of an "all-in-one" lens is that they tend to have fairly narrow maximum apertures, particularly at the longer ends of their focal length ranges. This limits the disparate angles from each side of the lens that the AF sensor can use to compare differences from the light rays striking one side of the lens from the light rays striking the other side of the lens.

Your lens is designed to have a very wide focal length range at a very affordable price. In order to provide that, the lens doesn't offer much in term of fast AF performance. It's not really made to excel at locking on to fast moving subjects.

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  • I think you mean "dynamic-area AF" instead of 3D tracking. Also called "d9" for example in the display. This mode uses the surrounding points as backup if the main point fails to lock. 3D tracking is for following a subject through the frame if you want to keep the background framing the same. imaging.nikon.com/support/digitutor/d5600/functions/…
    – Orbit
    May 19, 2020 at 14:42
  • this is very helpful, thanks. i thought it might be related to the lens, but for totally different reasons. is PZD also the reason the lens tends to make a click-clack noise in AF-C when there isn't much changing in the scene? (almost like it can't make up its mind between two slightly difference focus points)
    – Michael
    May 19, 2020 at 17:59
  • @Orbit No, I meant 3D tracking to follow the subject through the frame.
    – Michael C
    May 20, 2020 at 1:13
  • @Michael I've never used a Tamron lens with a PZD AF motor, but I have used the SP 17-50mm f/2.8 Di II that has no designation with regard to the AF motor. It seems to be a more conventional micromotor. It is a bit noisy. Some have complained it is slow, but I think it is decently fast and perhaps the louder AF motor makes it seem slower than it is to some folks? On the other hand, a 17-50mm doesn't need as critical AF because the DoF is deeper than a longer focal length lens would be for the same aperture.
    – Michael C
    May 20, 2020 at 1:35
  • Anytime you are in AF-C (or AI-Servo in Canon nomenclature), the lens will continuously refocus to track a moving subject. At no time will it "lock" to a specific distance and stop focusing until you fully press the shutter button. You could also be hearing the VC (vibration compensation) moving to counteract small camera movements. Does it make the smae noise if you turn off VC?
    – Michael C
    May 20, 2020 at 1:37
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Michael has already nailed exactly why this is so, but just to add anecdotally that with a very broadly-comparable setup; a newer Nikon D5500 & Tamron 70-300 4-5.6 I see very similar results.

The camera is fast enough, but the lens just isn't. It takes up to a couple of seconds to pull focus even in 'simple' conditions. If you add to that a rapidly-changing subject distance, it can never catch up in time & will often eventually refuse to even try.

On the other hand, if & swap to my Nikon 18-300 3.5-6.3, even though it would still appear to have similar limitations, the technology driving the focus pull is so much more advanced that I can actually get it to work reasonably effectively. I don't know precisely which technology either of these actually uses, but one is clearly more advanced than the other.
Of course, it's not perfect. If I really need 'fast' I've got a 50mm 1.4 which is lightning-fast, but for a long zoom, it's pretty respectable.

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    The newer Tamron lenses are much faster with regard to AF than most of the older ones. Of course they are also more expensive. The Tamron SP 70-200mm f/2.8 Di VC G2 is pretty much the equal of the EF 70-200mm f/2.8 L IS II in most regards, including AF speed. And it is more customizable thanks to compatibility with the TAP-in console dock.
    – Michael C
    May 20, 2020 at 1:16

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