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Waigy
Tinkerer
Username: Waigy
Post Number: 1
Registered: 02-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 05, 2013 - 11:03 am: | 
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I doubt if this lens qualifies as being a favourite classic, but before you escort me off the premises could you point me in the direction of a website that could help me?
Tamron 18-250mm f3.5-6.3 Di II Lens - Canon Fit.
Using manual focus on a Sony NEX-5n and a panasonic GH2.
When I zoom in to 250mm then focus then zoom out, the lens looses focus around 150mm and stays out of focus till 18mm.
If I then very gently push the zoom ring clockwise (still at 18mm) it comes back into focus and, if I carry on zooming in, it will stay in focus from 18mm to 250mm.
There is very slight play in the zoom ring which causes it to go into and out of focus.
I have uploaded two pics showing the difference when moving the zoom ring slightly.
www.flickr.com/photos/49720258@N05/8447015193/in/photostream
www.flickr.com/photos/49720258@N05/8447015025/in/photostream
My lens is still under a 6 month warranty, but as soon as I mentioned the word "problem" on the phone the guy immediately became defensive and just carried on being blatantly defensive no matter what I said.
I sent my lens to them and , as expected, they said they couldn't find any problems.
I had uploaded a youtube vid with a detailed explanation and two very easy to see examples of the problem, but if I had handed the lens to the guy and it was on fire he would still say it was fine.
I am now going to fix it myself, I have just stripped and rebuilt a minolta beercan with no problems and I am very good a fixing pretty much anything.
Does any one have experience of stripping this lens or have a link to a dissasembly?
Do you know the exact part to fix to sort this problem?
I have found this so far which is a slightly different lens.
www.clubsnap.com/forums/sigma-tamron-tokina/694767-slight... |
Br1078lum
Tinkerer
Username: Br1078lum
Post Number: 474
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 05, 2013 - 08:27 pm: |
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Sounds like you need to get a refund. If you bought it off the bay, take your problem to the next level, and let them sort the seller out. Other than that, I've no experience with AF zooms, so can't help you out.
PF |
Mareklew
Tinkerer
Username: Mareklew
Post Number: 281
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 06, 2013 - 02:19 am: |
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Waigy, this is the sort of a lens that is based around a lot of moulded plastic parts and the problem you describe sounds very much like one of them is cracked. It is hard to explain without pictures, but the AF lens group in zoom lenses is much smaller than the front element and is suspended in the center of the lens on a sort of a star made of plastic. If one of its arms is cracked you will still be able to focus, but you will perceive anomalies in the type of what you described. The maximum sharpness will also be impaired, but with a super-zoom there isn't so much of it to start with, so the damage might not be obvious at first.
Marek |
Glenn
Tinkerer
Username: Glenn
Post Number: 1053
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 06, 2013 - 06:43 am: |
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This series of lenses do not take kindly to DIY tamperings. From the sellers attitude I would suspect that he, or someone he knows, has had a look inside. Stop messing about and get your money back or you will just end up with a useless piece of junk. |
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