'Funky' Focusing Problem

[Shawner]

My D3000 AF-S 55-200 lens needs some medication. Seriously, for some reason, the lens cannot detect the object to focus in AF mode. The lens quickly tries to focus, but goes 'short' and 'long' (before and past) the object and never really settles on the object.

I have another lens that works perfectly. I have cleaned the entire lens, cleaned the mirror, cleaned the sensor, and I still have the same problem.

Any suggestions what it might be?

Cheers!

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[Big Mike]

What lighting conditions are you testing in? Some lenses will struggle more than others in low light.

[O|||||||O]

What you describe is usually called 'hunting'. It looks like it was nice and bright outside in that video ... did it do the same thing out there?

[Shawner]

Hey guys - thank you for the replies. The lighting is bright - focusing outside in settings that I've been in hundreds of times before. When I switch lenses to my 18-55, it works perfectly.

I am wondering if the lens has been jarred or bumped that could set the gearing / focal point off.

[Big Mike]

Another thing to check, is that you're not trying to focus on something that is too close...something that is within the lens's minimum focus distance.

But sure, it's entirely possible that the lens is in need of repair. Call your closest Nikon repair centre.

[bazooka]

Can you focus on an object manually ok?

[orb9220]

The 55-200vr has been my main walkabout last year. Yes if contrast low or no contrast will hunt & hunt find some defining edges like branches,lines,etc.. something for the lens to differentiate. Another is lower light and having camera on AF-S and Center AF point selected will engage the AF assist light to help slower variable lenses like this one. And lastly it is an all plastic lens and parts wear out.

Mine has been in constant use with over 10,000 images and daily use. So now is starting to balk when at 200mm and have to back off to 175 or so for AF to engage then go to 200mm. Also notice the AF speed is more sluggish now then when new. And this is a cheapy lens that can be picked up new for under $200. So it will be the first kind of lens to break or start to malfunction.

[marvinh]

Shawner - are you trying to focus through a window? As far a I can tell from the video, it looks like there is a window in front of the camera. Depending on the auto focusing system of the camera, it may be fooled by the window glass.

MarvinH

[Forkie]

Shawner - are you trying to focus through a window? As far a I can tell from the video, it looks like there is a window in front of the camera. Depending on the auto focusing system of the camera, it may be fooled by the window glass.

MarvinH

I was thinking this after seeing the video. There could be dust on the window which the camera thinks you are trying to focus on.