Nikon D7000 Back Focusing Issue?

[Maezyra]

Dear All,

As many of the D7000 owners may know, there is a known problem with these bodies back-focussing. Recently, I am finding more and more that the focusing is intermittently off. I always put this down to operator error (or Operator Erin, as my husband likes to call it), but now I am not so sure, especially after doing my research. I have not fine-tuned my lenses, mostly for fear of mucking it up and ruining the focus on my lenses. Is this an example of this back-focussing problem or is this indeed operator Erin? If this is the known back-focusing problem, how can I fix it and not stuff up my lenses in the process? If this isn't, is the problem that there is a sliver of background visible within the focusing square, which has tricked the contrast detecting part of the auto-focus into thinking that the background is the correct place to focus? Or, could it be a mixture of the two??

As you can see in this shot, the subject is not in sharp-focus and the background balloons are in focus, despite the focus point primarily being over the eye.

Thanks in advance,
Erin.

http://i1034.photobucket.com/albums/a425/Maezyra/BackfocusingIssue_zpsd2b12c23.jpg (http://s1034.photobucket.com/user/Maezyra/media/BackfocusingIssue_zpsd2b12c23.jpg.html)

[arthurking83]

I have to shoot off right now, but my comment is more of a bookmark for me to come back later tonight to comment.
I don't think the problem is really a backfocusing issue here, and I'll try to explain better with more time ... and post a small image of my explanation too.

[wedgtail]

Check here could be money well spent I have one . saved me from buying a dodgy lens on ebay I got my money back because I could prove the lens I bought was not fit for purpose massive back focus problem with it .

http://www.the-digital-picture.com/Reviews/Datacolor-SpyderLensCal-Review.aspx

[arthurking83]

Normally backfocus issues with regards to lenses or cameras, will see the backfocus amount limited to a few millimeters or centimeters at most. It's uncommon or rare, if not impossible to have a camera/lens backfocus issue(as in a well documented manufacturer problem) that displays such massive backfocusing problems.

In this image, the focus point is about 1m .. maybe more like 2m behind your chosen subject.

If this was a backfocus issue with your either of your gear(camera or lens), you would have seen this happen to every image, all the time .. and subsequently done something about it long ago.

If you aren't sure on how focus points operate, here's a quick rundown.

The focus square isn't actually a square at all, it's (generally) a couple of lines known as a cross type. (this is probably a gross simplification of the idea of them, but here goes).

107886
This is what a focus point actually is(disregarding the simplification)

Basically it's an overlay of a sensor onto a projected image(of the red square) where the red square is a guide as to where the focus points are.
The focus points are actually lines. But the two different parts of the system are not combined as one, and there are tolerances in the manufacturing process.
So what can happen is that the lines may not be centred as in the above diagram, but may look more like this:

107887

This doesn't mean to say that this is how your camera is currently set, but just a note that it can happen. I think there are tests to determine if your focus points are lined up, but it's not worth the effort, nor will it help in any way.
The idea is to understand that these sorts of things can happen, and could be just a small part of a multitude of circumstances.

How the focus works, is that it looks for the blurriness of the subject and constantly adjusts the lenses focus distance until it determines the sharpest or best looking subject rendering.
But it splits the image into two parts and sees and measures this split image using the thin black line system. For the system to work efficiently it needs the split image to be perpendicular to the sensor line.

107888
If your subject is a quartet of vertical lines, and your AF point is of the single types like the image above, focus will be impossible or hard to acquire.

So to diagrams of focus working or not look like this.

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Focus OK

107890
Focus NOT OK.

These are the basic principles of how the AF system in your camera works.
D7000 has a good focus system .. not the best, but very good. I think it had a 9 cross type AF point system, where 9 of the focus squares have this dual plane focusing ability.

So if the lady in the image was a quartet of coloured lines, she'd have been in focus if any one of those 9 cross type AF points were on her.

Your image looks to be either cropped, or in portrait orientation, and the focus point up high in the frame. This suggest that a non cross type focus point was used(like in the coloured lines line version of the AF type) . These focus point types are generally not quite as accurate as the cross types .. usually slower to focus, if they can at all .. depending on the subject matter.

So if you take some of this info, and put it together, you get the situation where your focus point(or more accurately the sensor) is not where you think it should really be, and that the sensor used was not sensitive enough to find any focus, and that the subject at the focus sensor had no detail for the focus system to acquire a lock.

I'll post a diagram overlay on your image to visualize what this could look like rather than relying on incomprehensible text ...

(but it has to be in another reply!!)

[arthurking83]

107892

So this is what may have happened here.

Look hard enough and you will see a faint cross overlay in the focus square box.
If this was the situation .. or worse the focus point was a single line .. then focus almost certainly would not have locked.
The camera simply focused where it thought you may have wanted it too .. basically infinity!

Apologies for the kiddy graphics .. my photoshop abilities amount to virtually zero(apart from squares and lines). :p
Actually I don't have photoshop, I used paint.net which I almost understand how to use.

Anyhow, the main point was that don't just assume the worst, as it may only cause you to stress over a simple situation where errors were involved.

I think that once you understand some of the shortcomings of these electronics doodads, you should be able to counter their quirks and foibles when they rear their heads.
(well at least that's what I tend to do .. ie. my non focusing 105VR comes to mind!! :rolleyes:)

Anyhow, I hope this helps somewhat.
I'd be inclined to some simple tests.

try focusing on a blank white wall.
try focusing with an outer focus square in a piece of paper with a thin black line, once with the line horizontal.
Next try it with the line vertical.

With that last test, the chances are that you may find it focuses one time, then the next time it loses focus .. if you're steady enough you can find an area in your outer focus square that may not focus at all.
if you try this same subject test with one of the central cross type sensors, it should focus spot on with every attempt.(as long as the black line is not drawn on black paper!! :D)

Basically in the image you posted, it wouldn't be surprising to anyone that the camera misfocused.

Easy solution to this occasional problem .. use AF-On focusing, or "back button" focusing as some folks like to call it.
What this means is that you set the AE-L/AF-L button to act as a focusing switch. You press it when you want to focus, you don't press it when you don't want to focus.
The idea is that if it doesn't focus, you stop pressing, and then press again for it to try again.
Even tho the idea behind it is still a random attempt to focus on something that may be hard to focus on, sometimes you're better off giving randomness an opportunity to do it's thing (ie. the test with the vertical line on the paper using the outer focus square!)

FWIW: I don't think your problem here was a regulation backfocus issue.

[I @ M]

I have not fine-tuned my lenses, mostly for fear of mucking it up and ruining the focus on my lenses.

You will not do any damage to your lens by performing AF fine tuning. You are adjusting the camera body not the lens and the process is entirely reversible by a couple of quick button pushes.

If you have a particulr lens that simply refuses to work in situations where others do then you can always have that lens calibrated separately in conjunction to your body.

[simonr23]

To OP, I have had the same types of issues on my d90, and had been convinced of back focus issues. Perhaps- after Arthur's excellent posts(thank you) it is/was simply a result of the focussing systems design/limitations. I had always thought the dhole square was measured, now I know better! They were very informative posts Mr King. Cheers again.

[Goatch]

I've got a D7000 that I have had to Fine Tune for every lens I hang off it , always back focus and after fine tuning it has been sharp as , setting is always about -12 , one day I'll drop it into a store to get it calibrated LOL , even my 70-200 VR11 was out on it and it's razor sharp on my D700 and D800 bodies . One thing I forgot to mention was there was nothing intermittent about my issue , it was there all the time on every lens .

[arthurking83]

I've got a D7000 that I have had to Fine Tune for every lens I hang off it , always back focus and after fine tuning it has been sharp as , setting is always about -12 ....

This was the point of my reply.

Try to understand the difference between backfocusing hardware(either camera or lens) and misfocusing.
A fine tune setting of about -12 on the camera equates to a few millimeters of focus in real terms.

Maezyra's image is focused about 1-2m behind the subject.

[Goatch]

Roger , I know that the difference in mine was only within 5cm from 3mtrs away , this may sound dumb but I used 3 spice bottles with the fine print facing toward me spaced about 5cm in front of and behind the central point spice bottle , then fine tuned the focus so the middle one I was focusing on was sharp , every time I started out the rear bottle would be sharp but my focal point was off .

[Maezyra]

Thank you so much everyone. Especially Arthurking83. The frustrating thing here is that I WAS back-button focusing for about a week before this christening and I changed it for the christening because I didn't want to stuff up getting a crucial moment by using a means of focusing that I wasn't that familiar with!! Darn it! I'll change it back for today. I'll try that white paper / square technique and see how things are going there. Again, thank you everyone for the VERY informative replies. It is greatly appreciated.

[arthurking83]

..... The frustrating thing here is that I WAS back-button focusing for about a week before this christening ..... .

using a separate af switch to enable disable the focusing system isn't for everyone, but generally those that do try it, and the other associated tweaks that go with it, find it a more natural way to photograph.

It's good that you at least tried it, and then reverted to your more comfortable workflow tho.

I'd recommend that you try it again, especially when you've got a bit of down time .. just to see what the actual benefit is all about.

Remember that if you do .. the real benefit(I think) in using the rear button focusing method, is that you are in control of the focusing.
That is, if the camera/lens is running in tangents to what you want(eg. as with this issue of focusing anywhere) .. a quick tap on the AF button(with your finger always half pressed on the release!!)
release the af if it's not focused on the correct area, repress again for it to fall into line .. and so on.
As soon as it's focused on the subject, and because you're already half pressing the shutter release, the instant the focus is got, you shoot.

Another couple of settings to get used too that complement this rear button focusing method is to set autofocus mode to continuous AF-C(as opposed to AF-S) .. and set the priority of the systems to release(if this is an option).
The 'release' priority setting allows you to expose at any time, even if focus is not made .. so it comes with the (occasional) drawback that sometimes you may get an occasional unfocused image.

The priority settings will be found in the Custom Settings Menu(pencil icon)
Priority in AF-C mode is menu item a1 and you'd set it to release .. although having a look a the menu system, it looks as tho release is already the default.

(leave AF-S priority to focus tho!!)

So remember, if you set the camera to AF-C and priority is set to release .. then you can fire the shutter at any time, focused or not!
If the priority is set to focus instead, then the camera has to acquire focus in order to allow the exposure to be made.

Both modes are handy for differing purposes.

[Maezyra]

using a separate af switch to enable disable the focusing system isn't for everyone, but generally those that do try it, and the other associated tweaks that go with it, find it a more natural way to photograph.

It's good that you at least tried it, and then reverted to your more comfortable workflow tho.

I'd recommend that you try it again, especially when you've got a bit of down time .. just to see what the actual benefit is all about.

Remember that if you do .. the real benefit(I think) in using the rear button focusing method, is that you are in control of the focusing.
That is, if the camera/lens is running in tangents to what you want(eg. as with this issue of focusing anywhere) .. a quick tap on the AF button(with your finger always half pressed on the release!!)
release the af if it's not focused on the correct area, repress again for it to fall into line .. and so on.
As soon as it's focused on the subject, and because you're already half pressing the shutter release, the instant the focus is got, you shoot.

Another couple of settings to get used too that complement this rear button focusing method is to set autofocus mode to continuous AF-C(as opposed to AF-S) .. and set the priority of the systems to release(if this is an option).
The 'release' priority setting allows you to expose at any time, even if focus is not made .. so it comes with the (occasional) drawback that sometimes you may get an occasional unfocused image.

The priority settings will be found in the Custom Settings Menu(pencil icon)
Priority in AF-C mode is menu item a1 and you'd set it to release .. although having a look a the menu system, it looks as tho release is already the default.

(leave AF-S priority to focus tho!!)

So remember, if you set the camera to AF-C and priority is set to release .. then you can fire the shutter at any time, focused or not!
If the priority is set to focus instead, then the camera has to acquire focus in order to allow the exposure to be made.

Both modes are handy for differing purposes.

Oh, yes, I'd definitely planned to go back to back-button focusing. I had only changed it for that one shoot because it was new and I'm always fearful of doing new techniques when other people are relying on me, preferring to become comfortable with "new things" in my own time. In fact, I switched back straight after the shoot and used it today (with far more focused results, which I am pleased with). I'm pretty sure my AF-C is already set to release priority, but I'll double check that next time my camera is out (yes, I do have that option on my camera and I have come across it before in my menu travels). I more often than not shoot in AF-C, mostly because I shoot moving subjects (in fact, I'm guilty of NOT changing it to AF-S when I am shooting static subjects, but that's a story for another time, LOL). I've had a quick review of my shots today, whilst using back-button focusing and pretty much all of them are fairly sharp on first glance. For the most part, I think I'll stick to that control for focusing. The only downside is that I have very small hands and it's a little bit awkward, but I'll get used to it.

[AnnieP]

I have the D7000, and changed to Back button focus last year and haven't had any problems with it. I much prefer it than the half depressing the shutter button - But then I had help setting it up in the first place! Good luck.

[NikonNellie]

I was back focusing with my D7000 and not had any issues either Erin. I liked it so much that I have kept using it on the D800.

[Maezyra]

I have the D7000, and changed to Back button focus last year and haven't had any problems with it. I much prefer it than the half depressing the shutter button - But then I had help setting it up in the first place! Good luck.
I was back focusing with my D7000 and not had any issues either Erin. I liked it so much that I have kept using it on the D800. I think I should clarify, the problem was not with Back Button Focusing, except that due to being less familiar with that, I decided not to use it for this gig. The concern was back focusing, which an entirely different thing (it's where the camera focuses behind the intended hit point of the focus point and sets the focus a few millimetres / centimetres behind the target, thus resulting in soft focus on the intended mark, requiring recalibration of the body's interaction with the lens to compensate for the shortfallings of the sensor.) However, after everyone's assistance, I think the problem was a combination of things, namely the focus point being used (ie. not likely to be a cross-hair type) her potentially moving between half-pressing and pressing the shutter and good old Operator Erin. I did another shoot on the weekend, where I let go of my worries about fumbling with an unfamiliar focus technique when doing something that someone else is relying on me for (ie. back button focusing, which I have been using in my personal work since finally making the jump {after using a certain D800 at my Nanna's birthday party} because if I fumble and miss a shot or muck it up, no one suffers but me), especially as it was a slower-paced shoot and I could take more time to concentrate and not panic when the half-pressing of the shutter that I have been using for 5 years and is ingrained in muscle memory doesn't work because I'm not in the habit of back button focusing yet and my hit rate was greatly improved. I used to not always get the focus I was after on moving shots using the half-pressing technique, because of that slight time delay from focus lock to opening the shutter, but this time, they were much sharper and I credit the positives of back-button focusing with this.

[Maezyra]

Forgive this part - My mobile device added the post twice.... Again.

[arthurking83]

Just another tip if you try the normal 'half press and shoot' method.

If you go back to your old setting of af on half press and focus priority, the camera's priority will be to operate only after focus is achieved. So in this mode of use, it's best to fully press the release.
This way, once focus is achieved, the delay time between focus and exposure is as minimal as can be.

The alternative of half press AND THEN full press has the issue of the human inflicted delay time between the two actions.
if if you are quick ... say 0.1s, the camera is always quicker .. say 0.01s.

So if you just want to check this for yourself.

Using your older method of not using the back button focusing method, line up your shot and fully press the release.
What will happen(or should happen) is that the exposure won't be made instantly, even tho you have fully pressed the shutter.
What will happen(or should happen) is that the camera will focus, beep and immediately make the exposure.

Note that setting AF-C mode or AF-S and back button focusing doesn't work with this full press action. The camera will almost likely take the exposure even without focusing.


I have this setup on my cameras in AF-S mode .. where the priority is focus.
I rarely use AF-S mode, and my reason for it is unique, in that I have(or had) only one lens that is CPU enabled, but manual focus only.
The CPU has been set so that as soon as the image is focused manually, the camera 'automatically' makes the exposure.(this feature is unique to the CPU chip used).

Also, good to see that you are making some inroads to your issue too.

[Maezyra]

Just another tip if you try the normal 'half press and shoot' method.

If you go back to your old setting of af on half press and focus priority, the camera's priority will be to operate only after focus is achieved. So in this mode of use, it's best to fully press the release.
This way, once focus is achieved, the delay time between focus and exposure is as minimal as can be.

The alternative of half press AND THEN full press has the issue of the human inflicted delay time between the two actions.
if if you are quick ... say 0.1s, the camera is always quicker .. say 0.01s.

So if you just want to check this for yourself.

Using your older method of not using the back button focusing method, line up your shot and fully press the release.
What will happen(or should happen) is that the exposure won't be made instantly, even tho you have fully pressed the shutter.
What will happen(or should happen) is that the camera will focus, beep and immediately make the exposure.

Note that setting AF-C mode or AF-S and back button focusing doesn't work with this full press action. The camera will almost likely take the exposure even without focusing.


I have this setup on my cameras in AF-S mode .. where the priority is focus.
I rarely use AF-S mode, and my reason for it is unique, in that I have(or had) only one lens that is CPU enabled, but manual focus only.
The CPU has been set so that as soon as the image is focused manually, the camera 'automatically' makes the exposure.(this feature is unique to the CPU chip used).

Also, good to see that you are making some inroads to your issue too.

i'll give that a try, thanks!! Although, I think I'll stick with back button focusing for now :)