Oh crap another d90 back focus thread

Started Apr 13, 2012 | Discussions thread
spbStan
Senior MemberPosts: 1,881
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Re: results, fwiw
In reply to Kris in CT, Apr 14, 2012

First off that curved surface and small target adds so much ambiguity to the AF that you have not learned anything from the test. The sensor for that FP is larger than the mark in the VF so the curved surface could easily have been locked onto at a depth well before or after the mark you put on the bottle.

The adjustment to the mirror box might make things better on one FL on one lens but will surely make it worse elsewhere. Factory alignment is not just mechanical, in fact little of it is, it is writing servo lookup table data to memory requiring special test jigs and software. Take it to a properly equipped Nikon service center and have them align and calibrate it. The one Macro lens that was worse might require rechipping by its manufacturer's warranty station. That is commonly required of Sigma and Tamron lenses but results are effective and cheap to do.

If one really wants to service their own d90, the service manual is available, i have one and you will see that there are a lot of interdependent calibration steps that are really screwed up by someone tinkering with the mechanical angle of the mirror. Why ruin a perfectly good camera, one of the most reliable and sorted out cameras every released in the Digital Era? At least read up on the real procedure and do it right.
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Stan
St Petersburg Russia

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