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02-05-2008, 12:53 PM   #1
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Zoom lens wobble, should I not tolerate it at all?

Just when I decided that my DA * 16-50 was okay (IQ-wise still is, I think), I noticed that when zoomed out, the extension tubes wobble (is this the correct word?) a little -- that is, when I grab the lens gently from the filter-holder-ring I can move the extension tubes sideways some fractions of a millimetre, so that at least the outer front lens moves a little against the lens axis. As far as I can observe the inner lens groups stay firm.

I have not noticed any effect to IQ or focusing, but this has begun to bother and I really hate having to worry about my lenses. My Tamron 18-250, which extends to really great lengths, does not wobble at all. I would have expected this DA * to be even more robustly build.

What do you think, if I decide to take it to Pentax representative for repair, can I claim the repair to be included in the warranty? Must I tolerate any wobbling from this lens?


Last edited by gawan; 02-05-2008 at 03:42 PM. Reason: language
02-05-2008, 01:54 PM   #2
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Hi Gawan

It's funny you should mention that:
QuoteQuote:
When zoomed out, the extension tubes of the (DA * 16-50) wobble....a little
When handling the K10D in earnest, I briefly used the 18-55mm kit-lens and DA * 16-50 outside the shop, before swapping them over to inspect the Sigma 10-20mm HSM wide-zoom, in which I was actually interested. At the time I distinctly remember being clearly surprised and slightly underwhelmed by the sloppy & insubstantial feel of both these Pentax lenses, whilst remaining satisfyingly reassured by the overall solidity & build quality of both the Tamron 18-250mm Di II & the Sigma 10-20mm HSM which I eventually purchased. Just my 0.2 cents worth.....

Best regards
Richard

Last edited by Confused; 02-06-2008 at 01:04 PM.
02-05-2008, 01:59 PM   #3
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Your post prompted me to check my T 18-250 now about a year old with quite a bit of use - no wobble. The only other PTX zoom I have is an ancient Cosmicar 70-210 bought new and used extensively - same thing, no wobble. Unless others w/your lens report wobble and are OK with it, I would raise H--L about it.............
02-05-2008, 06:57 PM   #4
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QuoteQuote:
Unless others w/your lens report wobble and are OK with it, I would raise H--L about it.............
Instead of being a hellraiser, why don't you just ask Pentax about it? If they say it is normal, then you have no reason to send it in for them to just return it saying it meets their specifications. Otherwise, if you are unhappy with it, sell it and move on.

02-05-2008, 08:12 PM   #5
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QuoteOriginally posted by gawan Quote
Just when I decided that my DA * 16-50 was okay (IQ-wise still is, I think), I noticed that when zoomed out, the extension tubes wobble (is this the correct word?) a little -- that is, when I grab the lens gently from the filter-holder-ring I can move the extension tubes sideways some fractions of a millimetre, so that at least the outer front lens moves a little against the lens axis. As far as I can observe the inner lens groups stay firm.

I have not noticed any effect to IQ or focusing, but this has begun to bother and I really hate having to worry about my lenses. My Tamron 18-250, which extends to really great lengths, does not wobble at all. I would have expected this DA * to be even more robustly build.

What do you think, if I decide to take it to Pentax representative for repair, can I claim the repair to be included in the warranty? Must I tolerate any wobbling from this lens?

Hi Gwan

I've just checked my lens after reading your post. I have three zooms (two Pentax and a tokina) and a Pentax prime and they all move somewhat, I note that you talk about fractions of a millimetre so we are not looking at a serious wobble. It's not really an issue with me but if you are concerned then I suggest taking SpecialK's advice and asking Pentex to comment.

Regards
Brian
02-05-2008, 08:41 PM   #6
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The only comparable zoom I have is the FA 24-90 (it has a lens barrel made of plastic like the ones you mention). It wobbles a bit, which is thought to be 'normal' for that lens. It was discussed on another forum some years back and all posters agreed that they had noticed any effect on image quality.
02-06-2008, 12:30 PM   #7
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Thank you for the replies - it bothers me enough that I will take it to Pentax repair workshop (which is fortunately at a walking distant from where I live) and ask for advice there. I will report back if you are interested.

And I tried to measure the wobble by sighting the movement against a ruler, it seems it is one whole millimetre

Last edited by gawan; 02-06-2008 at 12:44 PM.
02-06-2008, 01:04 PM   #8
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QuoteOriginally posted by gawan Quote
Thank you for the replies - it bothers me enough that I will take it to Pentax repair workshop (which is fortunately at a walking distant from where I live) and ask for advice there. I will report back if you are interested.

And I tried to measure the wobble by sighting the movement against a ruler, it seems it is one whole millimetre
Please do report back Gawan, I would like to know.

Regards
Brian

02-06-2008, 07:50 PM   #9
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QuoteOriginally posted by gawan Quote
Just when I decided that my DA * 16-50 was okay (IQ-wise still is, I think), I noticed that when zoomed out, the extension tubes wobble (is this the correct word?) a little -- that is, when I grab the lens gently from the filter-holder-ring I can move the extension tubes sideways some fractions of a millimetre, so that at least the outer front lens moves a little against the lens axis. As far as I can observe the inner lens groups stay firm.

I have not noticed any effect to IQ or focusing, but this has begun to bother and I really hate having to worry about my lenses. My Tamron 18-250, which extends to really great lengths, does not wobble at all. I would have expected this DA * to be even more robustly build.

What do you think, if I decide to take it to Pentax representative for repair, can I claim the repair to be included in the warranty? Must I tolerate any wobbling from this lens?
don't know about this lens, but it was one of the things I commented on with the 28-80 and 28-105 FA power zoom lenses and feeling cheap.

My 28-105 is now 16 years old and has never had any degradation in perofrmance but it does make you wonder.
02-07-2008, 01:35 PM   #10
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I took this lens to Pentax Repair Service today to have them take a look. Let's see what they will say. I'll report when I get it back.
02-07-2008, 11:10 PM   #11
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Interesting - I have a DA 16-45 f4 ED and the barrel wobbles at 16mm - spoke with the local Pentax dealer and we checked several others in stock. All did the same thing. Like other posts, I have seen no degradation in IQ. I did note at the time that the lens was assembled in Vietnam, but then other Pentax components are assembled in the Phillipines - all comes down to the cost of labor I suppose. Anyway, I am still a happy Pentaxian.
Would be interested to hear what Pentax say about the wobble Gawan.
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