D7100 Back focus issue

MolitorPhotography · Sep 18, 2015

I am having a terrible time with my d7100. I purchased it back in Feb as a Refurb product from Adorama, and everything seemed fine for a while. I primarily do portraits so It wasnt until my daughter started her sports later in the spring that I discovered an issue with the AF and by that time the 90 day warranty was gone.
The issue I am having is with moving targets. Any attempt to shoot an approaching subject is met with back focus. On a stationary target, everything is perfect, which means that I have to turn on AF fine tune if I know that I am going to shoot a moving subject and then turn it off again when they go stationary which isnt the most efficient thing to do.
I have this issue on every lens I have. I have tried every AF setting available with no success. as far as the current settings on the camera, I have it set to AF-C and D9. It is almost like instead of predicting focus forward on an approaching subject, it is predicting focus back... Here are a couple images I shot yesterday. you can see in the first image, although I focused on the front girl, the one in the rear is more closely in focus, and on the shot of the boy, if you look at his feet, you can see the grass area a couple feet behind him is in sharp focus. Does anyone have an idea if there is something I can do to correct it or am I going to have to bite the bullet and send it for service?

goodguy · Sep 18, 2015

I was going to give you few advices but after reading it all it seems like you covered all that I know, if this is an issue then I would just send it to Nikon.
Sorry wasnt much of help, good luck.

idcanyon · Sep 18, 2015

I don't think this is a true "back-focus" issue. Rather it is a matter of the AF-C tracking not being good enough. So I don't think sending it in for service is going to help.

I don't have a D7100 so I can't really speak with authority on how much performance this camera is capable of. I do have a D7000 and I occasionally use it to shoot soccer. I haven't paid attention to direction of motion specifically, but my experience is that it will jump focus in steps instead of doing it in one continuous motion, as is really needed. I get better results when I rapidly tap my finger on the shutter release button to make it snap into focus more frequently than I do just holding the button half way down.

astroNikon · Sep 18, 2015

idcanyon said:
I don't think this is a true "back-focus" issue. Rather it is a matter of the AF-C tracking not being good enough. So I don't think sending it in for service is going to help.

I don't have a D7100 so I can't really speak with authority on how much performance this camera is capable of. I do have a D7000 and I occasionally use it to shoot soccer. I haven't paid attention to direction of motion specifically, but my experience is that it will jump focus in steps instead of doing it in one continuous motion, as is really needed. I get better results when I rapidly tap my finger on the shutter release button to make it snap into focus more frequently than I do just holding the button half way down.

I used to use AFS-S just as you do on your d7000. FYI, I had a d7000 and currently a d600.
Now I use AFC-Single - the Single focus square to keep focus on EXACTLY the subject I want as I'm normally at f/2.8.

BUT upon testing lenses in the past some lenses were inherently causing focusing issues. One such popular lens like the Nikon 70-300 VR would continually miss focus which apparently was a common issue for it and moving subjects.

But the OP stated he had this issue on every lens, so I was stumped when I first read it, other than send it in to Nikon.

MolitorPhotography · Sep 18, 2015

Thanks. I havent been able to find more than a couple people online that seem to have a similar issue so I dont think it is a problem with the model itself, just my specific camera. I probably would have just chalked it up to poor AF performance in general if I was able to get a fair amount of in focus shots, but I am literally getting a 0% in focus rate on moving targets... They are all back focused which leads me to believe there is an issue with the autofocus system. I did update the firmware this morning and havent tested it since, but the notes on the update did not mention anything about autofocus so I doubt it will change.

MolitorPhotography · Sep 18, 2015

Im also concerned that I will send it in, and they will test focus on stationary targets and everything will be spot on, but fail to address the issue I have with moving targets, and when I get it back, I'll be in the same position. Do they have a way to lab test for moving targets in AF-C do you suppose?

astroNikon · Sep 18, 2015

Some cameras (not all) have had that problem including the d7000.
Some were able to get it resolved sending it to Nikon, others not.
no help .... but it is a known problem from time to time.

here was a checklist to check ==> Autofocus troubleshooting by Thom Hogan

wfooshee · Sep 26, 2015

You say AF-C, but are you including 3D tracking? That's supposed to add a predictive element. AF-C simply keeps something in focus in the frame, but locks at the time the shutter is tripped, and the focus may shift in the small amount of time it takes to activate the shutter. 3D tracking is (in my understanding) supposed to add a predictive element to the focus processing, by incorporating tracking of the subject distance while you hold the half-press and allowing for that movement during the shutter action.

SCraig · Sep 26, 2015

In my personal opinion that multiple focus point auto-tracking 3D nonsense does not work worth a crap. The times I've tried it I got exactly zero usable photographs so I gave up on it long ago. Like astroNikon I only use AF-C with a single focus point (not D9, "S") and then *I* decide where I want the focus point to be, not the camera.

Derrel · Sep 26, 2015

SCraig said:
In my personal opinion that multiple focus point auto-tracking 3D nonsense does not work worth a crap. The times I've tried it I got exactly zero usable photographs so I gave up on it long ago. Like astroNikon I only use AF-C with a single focus point (not D9, "S") and then *I* decide where I want the focus point to be, not the camera.

Do you know how to use it properly? Are you actually ASSIGNING the target at the start of the sequence, by using the 4-way controller to SELECT the initial target?

If you have gotten exactly zero usable photographs...you're not using the system right--at ALL. You ought to get at least 30%-40% keeper rate just by dumb luck.

SCraig · Sep 26, 2015

Derrel said:
Do you know how to use it properly? Are you actually ASSIGNING the target at the start of the sequence, by using the 4-way controller to SELECT the initial target?

If you have gotten exactly zero usable photographs...you're not using the system right--at ALL. You ought to get at least 30%-40% keeper rate just by dumb luck.

Probably not. If I have to go through a bunch of nonsense prior to pressing the shutter button halfway down then I reiterate that in my personal opinion that multiple focus point auto-tracking 3D nonsense does not work worth a crap.

wfooshee · Sep 27, 2015

With my D5000 at the Blue Angels end-of-season air show in 2011, I had a throw-away-due-to-out-of-focus rate of about 45 percent. The camera was not quick to focus, had only 11 focus points, and while 3D tracking was a selectable option, the small number of points and the distance between them had me thinking like you..... why the heck do they even offer this nonsense as an option? I wasn't trying to use it at the air show, or I would have had a higher throw-away rate.

One year later, I'd picked up a D7000, with a much faster AF system, and much denser sensor field with 39 focus points. I didn't buy any glass with it, just the body, and found it nailing focus with my same lenses at least twice as fast as the D5000. I also learned to use and practiced with the 3D tracking before I went to the show, and used it. 1400 frames over two days, and not one missed focus!!!

If you're seeing multiple points in the viewfinder, then you're not in 3D tracking. It only shows one active sensor, and whatever that one sensor locks onto when you half-press will be tracked and stay in focus, even if it moves around the viewscreen. You can see the camera selecting adjacent sensors to keep one on top of that object. The camera does not decide where the initial focus is, you do, by aiming the camera so the sensor is on the subject you want. You will NOT see more than one sensor active at any time in 3D tracking. The only "nonsense" you have to do before the half-press is aim so that the focus point is on your subject.... no different than AF-S for still life photography.

That said, if your subject is not significantly different in appearance than what's behind it, or simply too small in the frame, the tracking can be fooled and will shift its lock onto the background. I can't use 3D tracking for bird-in-flight photography, for example, unless the birds are well up out of the trees, or quite close. There is a menu adjustment for how long a delay the camera will have before shifting focus a significant distance, which is meant to address that issue, but for BIFs I haven't found a good balance. Birds are just too close to the same colors as the background, offering the sensors no contrast.

It's worth a shot for the OP if it's not something he's tried.

wezza13 · Sep 27, 2015

wfooshee said:
With my D5000 at the Blue Angels end-of-season air show in 2011, I had a throw-away-due-to-out-of-focus rate of about 45 percent. The camera was not quick to focus, had only 11 focus points, and while 3D tracking was a selectable option, the small number of points and the distance between them had me thinking like you..... why the heck do they even offer this nonsense as an option? I wasn't trying to use it at the air show, or I would have had a higher throw-away rate.

One year later, I'd picked up a D7000, with a much faster AF system, and much denser sensor field with 39 focus points. I didn't buy any glass with it, just the body, and found it nailing focus with my same lenses at least twice as fast as the D5000. I also learned to use and practiced with the 3D tracking before I went to the show, and used it. 1400 frames over two days, and not one missed focus!!!

If you're seeing multiple points in the viewfinder, then you're not in 3D tracking. It only shows one active sensor, and whatever that one sensor locks onto when you half-press will be tracked and stay in focus, even if it moves around the viewscreen. You can see the camera selecting adjacent sensors to keep one on top of that object. The camera does not decide where the initial focus is, you do, by aiming the camera so the sensor is on the subject you want. You will NOT see more than one sensor active at any time in 3D tracking. The only "nonsense" you have to do before the half-press is aim so that the focus point is on your subject.... no different than AF-S for still life photography.

That said, if your subject is not significantly different in appearance than what's behind it, or simply too small in the frame, the tracking can be fooled and will shift its lock onto the background. I can't use 3D tracking for bird-in-flight photography, for example, unless the birds are well up out of the trees, or quite close. There is a menu adjustment for how long a delay the camera will have before shifting focus a significant distance, which is meant to address that issue, but for BIFs I haven't found a good balance. Birds are just too close to the same colors as the background, offering the sensors no contrast.

It's worth a shot for the OP if it's not something he's tried.