AF problems: the body or the lenses?

[Tommi14]

I took my D700 to the local official Nikon service for check, clean and adjustment because it front-focused with most of my lenses. In the service, both the mirror and the af mechanism were adjusted. Unfortunately, this had only a minor affect to the focusing and the problem remains. According to the service, the body is now in factory specs and the problem must be in the lenses. However, I find it hard to believe that most of my lenses are front-focusing quite a bit.

Below are the "Default" AF Fine Tune values that I am using with different lenses at different focal lengths at the moment. The lens specific values equal approx. 2.5 times these values, i.e., +20 at the maximum.

AF-S 24 mm 1.4G
24 mm, +3

AF-S 35 mm 1.4G
35 mm, +4

AF-S 85 mm 1.4G
85 mm, +6

AF-S 14-24 mm 2.8G
14 mm, +1
24 mm, +7

AF-S 24-70 mm 2.8G
24 mm, +8
35 mm, +3
50 mm, -1
70 mm, +6

AF-S 70-200 mm 2.8G VR II
70 mm, +3
85 mm, +1
105 mm, +2
135 mm, +3
200 mm, +6

I have obtained the values by the "Dot Tune" method and have checked them by other methods. Also, the values seem to work quite well in normal photography as well.

To me it looks like that the body must still be out of the specs. I mean, what are the odds that all the six lenses are front-focusing more or less in a similar way? However, to confuse more, I quickly tested the 35 mm and 85 mm primes with my father's old D40, and they looked like to front-focus with that body as well.

So, I am quite clueless what to do next. Should I take the lenses to the Nikon service? Or should I just keep using my gear with the above AF Fine tune values?

My concern is that after the service the lenses would be more messed up or hurt some other way.

I will most probably replace my D700 by the successor of D810. So, I might wait and reconsider the situation once I have the new body. On the other hand, the three primes are still under the warranty for a few days/months.

What would you do?

Best regards,
Tommi

[Ilkka Nissilä]

Your values seem typical and vary in a fairly small range around the mean. I think this is close to as good as you can expect and you should be happy! ;-)

[Tommi14]

Thank you for cheering up! Did you notice that the presented values are "Default" values, not lens-specific values? The lens-specific values seem to equal approx. 2.5 times the "Default" values. So, if I wanted to save specific values for each lens, I would need to dial +15 for AF-S 85 mm 1.4G. Would you consider that value typical?

Best regards,
Tommi

[Ilkka Nissilä]

Okay then they're a little on the high side (I didn't realize what you meant by "Default"; why would you use that instead of the lens-specific value?) both in terms of mean and variability from lens to lens.

[PedroS]

I used to be upset with different AF tune values respective to different lenses...
Not anymore, as long as they are within tuneable range and the pictures came perfect, that's all I need.

I do bring with me all the time the data for all my lenses so I can modify/return as needed.

[Akira]

I would have the Nikon service to calibrate the lenses.  I've made it into a habit.  Both of my AF-S 50/1.8G and AF-S 24/1.8G had off-focus problem, but after the calibration at Nikon, I don't even need to turn on the AF fine tune function in the camera (D750).

[Tommi14]

Thanks for your responses!

I am using the non-lens-specific default tune value because all the six lenses need roughly the same amount of correction. Also, I have found that the tune value needs to be slightly adjusted for different conditions anyway, so I find little use for lens-specific tune values. In addition, the non-lens-specific default value has wider effective adjustment range.

Because all the six lenses need roughly the same amount of correction, I thought that the problem was body related. I was hoping that after the service the mean of the needed tune values would be close to zero. However, that was not the case.

Best regards,
Tommi

[Akira]

The problem of the in-camera AF fine tune is that the best value varies according to the focusing distances, which is pretty annoying especially if you use one lens from closer shots, street snaps to landscapes.  I use most of my lenses that way.

After the calibration at the Nikon service, the lens focuses accurately at all distances without relying on the AF fine tune.

[Ilkka Nissilä]

While all my cameras require some fine tuning only the D800 I had suffered from significant distance dependent focus errors; all my other bodies seem to focus fine after adjusting each lens to the body using the lens specific fine tune setting optimized for an intermediate distance. It seems that to get that kind of distance dependent effect (that is noticeable enough to be a practical issue) has to be wrong in the body, either its calibration (software or hardware) or its design in the first place.

Near MFD however there may be such an issue, because a lens may change its internal configuration quite a bit towards closest focus. I simply don't expect perfect AF at MFD and use AF throughout most of the range successfully.

The D800 I had was excellent image quality wise but it caused major headaches with most of my fast primes regarding AF. I am glad it was an anomaly.

Interestingly some lenses did work excellently with even that body; 70-200/2.8G II and 200/2 II didn't have any AF issue with it, except for the color dependence of AF error with the 200/2. This and the distance dependent AF errors seem absent in my D810 or are so small that I can't conclude that they are present.

[Akira]

While all my cameras require some fine tuning only the D800 I had suffered from significant distance dependent focus errors; all my other bodies seem to focus fine after adjusting each lens to the body using the lens specific fine tune setting optimized for an intermediate distance. It seems that to get that kind of distance dependent effect (that is noticeable enough to be a practical issue) has to be wrong in the body, either its calibration (software or hardware) or its design in the first place.

Yes.  I should have added that my cameara bodies (both the current D750 and D7000 I used previously) were also calibrated at the Nikon service.  They worked on either on the deeper firmware basis (unreachable by the user) or on the hardware basis (AF block?).  All the lenses and bodies were bought brand new.

[David H. Hartman]

Off the top of my head I'd take the holly trinity and body to Nikon for adjustment. I would like to take my D800 in but can't afford it now.

Dave