Nikon D90, Sluggish AF with Nikkor Micro 40mm 2.8

[nikos_k]

<p>My D90 has developed some strange behavior. When using my Nikkor Micro 40mm 2.8 it focuses painfully slow to infinity. With my Nikkor 50mm 1.8 AF-D the action is fast and snappy. <br>

I have tried the Nikkor Micro 40mm 2.8 on my Nikon F-100 and it focuses reasonably faster. Is this a lens or camera problem?</p>

[heimbrandt]

<p>When you say "has developed", I take it your D90+40/2.8 have not always been this slow?</p>

<p>Could it be as simple as someone accidentally has touched the focus limiter switch? If not, you have a problem somewhere. The 40/2.8 has a very long throw, so it is not as fast as the 50/1.8, which has a much shorter throw from infity to its close focus limit. The 40 has a focus range limiter for that reason. How is your switch set? Your 50 is also faster, which makes the job easier for the camera to find contrast on which to lock focus.</p>

<p>The fact that it takes more time to find focus could also be the result of a more exact algorithm.</p>

[Wouter Willemse]

<p>Another option, given that it works OK on the F100, and the AF-D 50mm f/1.8 being a non-AFS lens could be a dirty contact in the lens mount on the D90, limiting the communication with the lens. It's a long shot, though.</p>