D90 Back / Front Focus DIY

[FoolyCooly]

One of my D90s has always been a little off when focusing on objects at a distance. I recently purchase a Tamron 28-75 f2.8 and was horrified by the results. Mush, mush, mush at any focal length and distance so I performed the procedure linked below to adjust the focusing mirror.

http://www.howtoshot.com/82/how-to-fix-front-focus-nikon-d90-d80-back-focus-problem/

After 4 attempts, this lens and all my lenses are tack sharp. There is no difference in sharpness between AF and live-view (contrast detect AF). Wow, I wish I had done this sooner. Now I'm debating adjusting the AF on our other D90 which is just ever so slightly off.

The body I adjusted was under warranty but I did it anyway since I'd rather not send it out for work.

 

[Graystar]

If you try this on the other D90, use the sensor-cleaning process to lock up the mirror. The reason is that the sensor-cleaning process also opens the shutter. If you slip with the hex wrench and touch the sensor, you might damage the AA filter...but that can be removed. However, if you slip and touch the shutter, you will definitely damage it and your camera will be useless.

.

 

[FoolyCooly]

Good point. Thanks for the tip!

If you try this on the other D90, use the sensor-cleaning process to lock up the mirror. The reason is that the sensor-cleaning process also opens the shutter. If you slip with the hex wrench and touch the sensor, you might damage the AA filter...but that can be removed. However, if you slip and touch the shutter, you will definitely damage it and your camera will be useless.

.

 

[FoolyCooly]

Our 2nd D90 has been more challenging to adjust. The top center focus point has always been off. It has always slightly back focused. After tweaking the eccentrical stoppers for both manual and autofocus, it is much closer but requires some fine adjustment. Honestly it's hard to believe that both of these bodies made it out of the factory this far out of calibration.

I think some users complaining about soft lenses would be surprise to find that their autofocus is not calibrated properly. It's amazing how sharp all my lenses are on the first body I adjusted.

 

[Limaunion]

thanks for this info, I've just bought a new D90 kit and hope not to require to use this procedure never in my life... (but will keep the link for future reference).

I wonder if the D90 is the only model affected by this misalignment...

 

[FoolyCooly]

NP, I doubt the D90 is the only model effected by FF/BF issues. You'll see reports here and there for other bodies as well. All together I've owned 4 D90 bodies. The two I currently have are the only ones that have ever given me any trouble.

This 2nd body is going to need to be serviced. The is no independent adjustment for the top and bottom focus points. I wish I had access to the D90.exe inspection and adjustment software.

thanks for this info, I've just bought a new D90 kit and hope not to require to use this procedure never in my life... (but will keep the link for future reference).

I wonder if the D90 is the only model affected by this misalignment...