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08-21-2012, 02:04 PM   #1
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Tamron 70-300 focus problem

Hi Guys,

I have a Tamron 70-300 zoom lens which I use with my Pentax K-r. A while ago when we were visiting Australia I dropped it by accident onto concrete. Luckily it survived with very minor damage and worked fine. I've had it in my camera bag for a while and haven't used it. I got it out today to find a long crack in the barrel which is visible when zoomed. It seems to have focussing issues now and struggles in AF to find a focus point. Sometimes it focusses fine but mainly when not zoomed in. When zoomed it seems to struggle to focus. What I can't understand is how it's suddenly stopped working, the crack looks to be only to the outer plastic and the optics seem fine. Is this one to claim off my insurance? Is it likely to be a very expensive repair? I can post pics if it helps.



08-21-2012, 02:18 PM   #2
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It sounds like it's bleeding light into the barrel when you have it extended beyond 70mm. If there are no cracks in the elements, I would look for someone local that can repair the barrel. It may be expensive if they have to remove the elements and replace the barrel. If they can just repair the barrel it may be a cheap fix. I feel for you; it is my biggest fear, dropping a lens out in the field. I have a very strict ritual for switching lenses outdoors. I find a flat, clean surface to rest the lens I plan on mounting to my camera, lay it lens cap down and loosen the rear cap. With my camera strap around my neck, I dismount the lens on my camera, lay it lens cap down next to the other lens, take the loose rear cap off and place it on the lens I just dismounted, then mount the replacement lens. Then I tighten the rear cap on the other lens. Then the dismounted lens goes in the bag.
08-21-2012, 02:37 PM   #3
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With the price of that lens I expect it will cost more to repair than to replace it, so perhaps it is time to notify your insurance if the deductible is low.
I really like my Tamron 70-300 personally, it is a very versatile lens..
08-21-2012, 02:48 PM   #4
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Have to agree with Larry on this one - apparently time to write this one off - sorry.

08-22-2012, 11:31 AM   #5
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You have nothing to loose, try to glue the crack with a black epoxy and sand it smooth

08-22-2012, 12:25 PM   #6
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QuoteOriginally posted by hnikesch Quote
You have nothing to loose, try to glue the crack with a black epoxy and sand it smooth

Before you go to that effort you could try an experiment with a thick black cloth over the body of the lens, thereby blocking light getting into the barrel, and see if that significantly improves its performance. If it does then going forward with black epoxy filler would make sense.

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