subject-tracking

[Peeshan]

(dear admin, sorry for the bother if you have to move this post to an existing thread)

So today I remembered that the focus tracking ability of my D7000 was one of the reason I bought it, and that it could possibly greatly improve my bird photography.
But how does it work?
It indeed track very well the selected subject, but as soon as I press or half press the shutter the tracking freeze - wich kind of miss the point. Any idea what I am doing wrong? Or is it reserved for video?

[Ido]

It's because the shutter button is configured to lock both focus and exposure. I don't own a Nikon DSLR camera, so I can't tell you specifically how to do it, but try delving into the menu (or better yet - the user manual provided with the camera / downloadable PDF from Nikon's website) until you find the settings for AE-L / AF-L (it's a button on the back of the camera, to the right of the viewfinder).

There is a method called "back button focus," which utilizes this button to separate the autofocus actuation actuation from the shutter button. The AE-L / AF-L button should act as AF-ON (look for that bit in the settings). Pressing it will start the autofocus, releasing it locks the focus at whichever position it last was.

I'm certain there a way to get the half-press of the shutter button act as AF-ON instead of AF-L, but again, since I'm not familiar with Nikon DSLRs, I can't tell you how to do that. Read through the manual, that's the best advice I can give.

[Peeshan]

I see. I know how to do that, I will do some tests, thanks.

[Manfred M]

I am not a bird photographer, so do not know the intricacies of this form of photography, but am a frequent user of the motion tracking for focus, using the back-button method. I tend to use this technique in street photography. I use a centre point focus (focus on the eye nearest to the camera) and then I recompose and press the shutter release. I tend to shoot with a very shallow DoF, so getting the focus right is critical.

I find that AF-C focus works best when the subject is moving either towards me or away from me; i.e. perpendicular to the sensor (back and forth motions). It really does not buy me much when the subject is sitting still or moving parallel to the sensor (left to right / right to left motion).

I have not tried the 3-D focus mode (not sure if the D7000 has this; the D800 does for sure); but I find the same issue as with all of the multi-point focus modes, it rarely picks the focus points that I want.

[Mike Buckley]

I have not tried the 3-D focus mode (not sure if the D7000 has this

It has it.

[PhotomanJohn]

I think there is still some confusion here. For any focusing to occur either the shutter button has to be half pressed (default camera setting) or the autofocus has to be assigned to the AE-L AF-L button and it must be depressed. I don't understand the OP's comment that the focusing is tracking until the shutter button is depressed (normal configuration) because until the shutter button is pressed the focus function is off. Assigning focus to the rear button (highly recommended) does not change the focusing function, just how one initiates it.

There are two levels of focus tracking in the D7000 and other Nikons. First the camera must be set in either AF-A (auto) or AF-C (continuous) focus mode (pg. 91) to have the focus track a moving subject. If the camera is set to AF-S (single) then the camera will focus once when the shutter is pressed halfway (or rear button if so programmed) and then will make no more focus changes until the button is released then re-pressed.

To focus continually to follow motion the camera must be in the continuous focus mode either by setting it to AF-C or to AF-A in which the camera is supposed to detect subject movement and automatically switch to AF-C. In addition the "focus button" (which ever one) must be held continuously. Also note that if the AF Area Mode is set to single point then the subject needs to maintained in the center of the view finder for it to be tracked.

The second level of focus tracking is called 3D tracking (pg. 94) that takes into account the subject's color to try to more effectively track the object even if it momentarily goes out of the screen. For this to work you must be in a continuous tracking mode (AF-A or AF-C) as mentioned above.

The bottom line is that to focus track a subject, it doesn't matter which button you use to activate focus with. The camera needs to be in AF-A or AF-C focus mode (not AF-S) and the button has to be held continuously. If you want take advantage of their advanced 3D tracking (never tried it) then the AF Area Mode setting needs to be in 3D tracking not single point or dynamic in addition to the camera being in continuous focus mode.

I know this can be somewhat confusing and hope this background helps. Let us know if you still can't get it working and we will help you sort it out.

John

[Peeshan]

> PhotomanJohn: what I meant is that the tracking stop, ie. it focus on the point where the subject was at the moment I started pressing the shutter, instead of continuing to follow.

Yeah, sorry if there was a misunderstanding, I was speaking about the LiveView-tracking mode by the way, where you first lock your subject with "ok", but after several trials and comparisons with the viewfinder it appears that it is indeed for video - it's very effective for video by the way - that's why pressing the shutter messed with it.

Still, thank you all for the input.

> GrumpyDiver: i believe in your case 3D matrix could be useful, especially since it works with color detection and often peoples tend to be more colorful than their environment.

[PhotomanJohn]

Peeshan - I understand now that you were talking about the AF-F mode in Live View and yes it does focus continuously until you press the shutter button and if the Area Focus Mode is set to tracking then it will track a subject. On the other hand, AF-C when looking through the viewfinder will track while you hold the shutter button half way. I didn't think that you might be talking about Live View because I find it difficult to photograph moving objects that way as compared to using the viewfinder.

Anyway, welcome to CC.

John

[Manfred M]

GrumpyDiver: i believe in your case 3D matrix could be useful, especially since it works with color detection and often peoples tend to be more colorful than their environment.

I have not been all that impressed with the multi-point focusing modes, and I prefer to pick my own focus point. However, I will do some testing with the 3-D focus mode to see if it does something for me.

As for shooting with LiveView when birding; that seems like a very odd way of shooting birds with a DSLR. Using the viewfinder and tracking in flight is the technique that I've seen used most often. LiveView tends to be limited to speciality shooting and video work on a DSLR.

[Mike Buckley]

LiveView tends to be limited to speciality shooting...

For others reading the thread, I know Manfred understands that it's also great for any photography being done with a tripod such as product and landscape photography. Neither type of photography is pertinent to this thread, which is discussing how to focus on moving subjects.

[chauncey]

I can't speak for Nikon, but for us Canon folks there are some very specific custom functions that allow us to dictate how that "follow focusing" is achieved. Proper custom function settings are important for us.
Regardless...keeping that bird within the viewfinder is kinda important.

[Peeshan]

Actually I never used the Live View until now, I wanted to see if it could give an advantage over the viewfinder - you are right, it doesn't (handheld anyway).

For the record and eventual other experimenting with AF, I found that my initial "low-quality" tracking was mostly due to the customs setting Chauncey just mentionned (on Nikon camera: a. autofocus > a3. tracking and focusing) being messed. Also the back-button focusing seems very powerful, it seems easier for the brain to assign one task per finger instead of half-press-press-release-halfpress...

[ajohnw]

For bird photography I suspect the "focus now" while holding a button down will be rather cumbersome. The OP should just need to disable the focus lock on 1/2 shutter press. Exposure locking too. When the shutter is 1/2 pressed the AF tracking should engage.

I saw a video advocating the focus now button arrangement for wild life saying "the subject might move". If tracking is on well it will track so what's the point. Where it is very useful is when the camera needs to be focused at some other distance than where it would naturally focus when the shot is taken.

I've not explored 3D tracking but if it's similar to a facility on one of my cameras it might not be a good idea. In difficult focusing situations it may start tracking some thing else in the frame so I stick with centre only when that may happen. Some cameras also have a don't shoot unless in focus setting - can be a bit frustrating unless the af confirm indicator is checked before taking the shot.

John
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