I'm a newbie to photography and the forum. I've been taking pictures for years and learned anything I know by trial and error and reading. Mostly trial and error! I recently purchased an 18-200mm Nikon lens used from
Andorama. When using it on M/A, it is usually ok but at times it will stop autofocusing for a while and then start to autofocus fine. This has happened 2 or 3 times since I bought it. Is it something I might be doing or maybe the lens. I have 3 other Nikon lens that work fine, a 18-55, 70-300, 10-20mm. Any ideas or suggestions would be appreciated.


  • Assuming you are familiar with how auto focus works, and have not experienced a similar issue with the other lenses, I'd guess that the issue is in the lens. One thing to try is to clean the contacts on the lens (use something appropriate to the job, not a pencil eraser which leaves junk and causes wear). You might just also try wiggling the lens in the mount to see if it's a contact issue. If that works, then a little contact cleaner might solve it. Otherwise it might be something internal to the lens. At one point I had a similar issue with a 55-300, which seemed to respond to switching back and forth between AF and M. It's not done it recently, but I suspect the switch was a little dirty or making poor contact. I had just gotten this as a replacement under warranty for one whose auto focus completely failed, and was on safari in Africa. I almost threw the lens into the jungle, but after a couple of angry flicks and bangs, it recovered.

    In the "something I'm doing" category there's not much, except to make sure that the focus point is where you want it and has not wandered off into the sky by accident, and that the lens is not just being lazy when the focus is near to where it ought to be. For that latter, try aiming at something way out of the current focus point, and see if it wakes up.

    But if the problem is frequent and does not respond, your best bet may be to return the lens if you still can, and save your sanity.
  • Thanks Bruto! I cleaned the lens contacts and it seems to be working ok now. (So far!) I've got a few days left to return the lens if necessary.
    I'm going to use it a lot the next couple of days and see if the fix lasts.
    Thanks again!!
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