D750 AF issue after service related to shutter issue

[PeterN]

Hi,

I have run into an issue that I have not experienced before: heavy front-focusing. This happened after a service by the Dutch Nikon Service Point related to the shutter issue. Although I did not have such an issue they told that it could happen at any moment in time. But since I got my camera back I do have a focusing issue. Everything seems to work fin in Live View but not when I use the optical viewfinder things go wrong. I was pretty pxxxxd because it screwed a shoot I had shortly after. Also angry at myself that I did not check.

I just checked the focusing-issue with a proper procedure (tripod etc) and I can confirm the issue is there, at least for three lenses I tested.

Any recommendations/advice? Am I nuts? Could the issue be caused by the service?

PLease forgive my ignorance w.r.t. these type of issues.

Thank you,

Peter

[Ilkka Nissilä]

Which lenses do you use that exhibit the problem? If they are fast primes, fine tuning is commonly needed. If it is f/2.8 or slower lenses that show inaccurate focusing then probably something went wrong in the service. Make test shots and print some crops and send the camera back with illustrations of the problem. You can of course get familiar with the "wonderful" world of autofocus fine tuning but if you haven't needed to do so in the past, it may be easier to let Nikon try to fix the camera. Best of luck.

[pluton]

Definitely supply the service place with photo examples...prints or JPEGs.

[Ilkka Nissilä]

Just something that came to mind: sometimes they turn off AF fine tuning at service. The recorded settings sre still there in the camera's memory but the feature needs to be turned back on to get back to normal operation. They may have also recalibrated the AF with a reference lens which means I have to do the tuning to each lens again. Tough life. ;-)

[Akira]

Peter, sorry about your annoying trouble.  If the trouble emerged clearly after the service, the re-assembling failure (the sensor not sitting on the correct image plane) might be the culprit.

A properly calibrated lens/camera combo should work without problem even without the focus fine tune in the camera menu.  My D750 and AF-S 50/1.8G combo (both bought new) had a slight de-focus issue which was addressed by the calibration at Nikon service.  The AF-S 24/1.8G that I purchased as second-hand in a pristine condition showed also a slight focusing error which was addressed after serviced at Nikon.

According to the explanation by the service person at Nikon, AF-S motor should be stopped at the right position when it receives the "stop" command from the camera, but it can be misaligned for whatever reason, which causes the focus error and needs re-calibration.

[PeterN]

Thank you so much for your help! Highly appreciated.
I think I will go back to the service center with examples.
I tried 35mm 1.4, 58 1,4, 60 2.8 macro. Didn't bother to try the zooms and other primes because these lenses showed the same focusing error.

[Akira]

Good luck, Peter.  You could just take your sample jpeg files in a USB memory stick or on an SD card...

[pluton]

Good luck, Peter.  You could just take your sample jpeg files in a USB memory stick or on an SD card...

Or on a low-cost CD or DVD that is affordable to give away, although in the past, my experience Nikon service has been conscientious about returning the customer-supplied media.

[JohnBrew]

I had a similar problem with my D810. After a shutter replacement and CLA my 70-200 f4 could not be made to focus no matter how far I went with fine tune. Turned out it was the lens and it was repaired under the lens warranty. When returned no fine tune adj. was required at all.

[PeterN]

I am one step further in identifying the issue. The focusing error occurs when there is depth, e.g a face. I tried with a book with the word "writing". While I focused on TIN via the optical viewfinder RIT turned out to be sharp. When I focused via LiveView on ITI, this was sharp. The focusing error does not occur when I am fully parallel to the object, eg a test chart. Both in OVF and LV.

I did contact the Nikon Service Center in the Netherlands and guess what they told me to do: to finetune myself. They said they performed the finetuning according to the procedure. Can you believe that? I told them that I screwed up a part of a shoot because of this issue and that I thought they should take care of it because the issue did come up after the shutter unit replacement. So now I have to send the device for repair again.

Will keep you posted....