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Old Feb 23, 2010, 3:28 PM   #1
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Default faulty lens? what now?

ok so i got the pentax da 12-24mm f4 lens and first time i took it out i was rushed and light was failing fast so didn't think to much over the poor result - just put it down to trying to hand shake

today i took it out again and well am not impressed - f8 shot from a sturdy tripod with 2 sec timer mirror lock up and results are fuzzy

now went back and reread the reviews of this lens on pentax forums and general opinion is this is a very sharp lens so i gotta figure the lens is faulty

will upload some full size images for you to examine so you can see for yourself

http://farm5.static.flickr.com/4012/...84592743_o.jpg - from tripod

http://farm5.static.flickr.com/4068/...cc2f74dd_o.jpg - hand held

anyway i bought the lens from online retailer through amazon.co.uk and have the invoice that came with it and the warrantee card but its not been stamped and it says its not valid unless its been stamped!! what do i do about this?

if that warrentee thing isn't an issue then what do i say? sorry this lens jsut aint as sharp as it should be? how do you objectively measure that? advice anyone?
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Last edited by John.Pattullo; Feb 23, 2010 at 6:21 PM.
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Old Feb 23, 2010, 3:56 PM   #2
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The subject in the foreground (boat) looks plenty sharp to my eyes. The trees in the background dont look as sharp, but then again, they are in the distance. I could not access the picture which was taken hand held.

If I were you, I'd subject it to some additional testing...photograph the usual brick wall, signage with lettering, to confirm that the lens is faulty. For a wide angled lens, however at f/8, depth of field should be pretty good to accomodate most of the picture in focus.

Can you return it to the seller for an exchange? I typically only purchase from Amazon directly since they offer a 30 day return window in the US.

You can try to contact Pentax and explain your situation in regards to the stamp on the warranty...not sure how you would obaiin a stamp on the warranty card on an on-line transaction.

Sorry to hear about your troubles....I know it can be frustrating especially when you spend a lot for a lens. Hope you can find a resolution!
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Old Feb 23, 2010, 5:11 PM   #3
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I am just taking a guess at the problem... don't mind me if I am off... First, your second link did not open, so I only looked at the first one with the tripod. Would you be willing to try again, this time 1 second or something... I know you used a tripod, but were there any strong winds... an odd strong gust? Ned
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Old Feb 23, 2010, 6:27 PM   #4
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not so much as a breath of wind and since was using f8 on wide angle i expected a deep dof so actually focused on the treeline in the distance

the boat does look marginally sharper but think its jsut because it has hard lines and being closer is larger

will try some tests on more easy to analyse subjects but i definately think there is something wrong with this lens

i fixed the link to the second picture
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Old Feb 23, 2010, 7:01 PM   #5
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if you have the receipt call pentax and have it fix it.
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Old Feb 23, 2010, 7:05 PM   #6
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the warrantee says that it needs to be stamped to be valid - will pentax accept it without the stamp but with the reciept?
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Old Feb 23, 2010, 7:08 PM   #7
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Well in the US, they do care about the card, just proof of purchase. Best thing to do is to call pentax.
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Old Feb 23, 2010, 7:10 PM   #8
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Also when I had a problem with my oly point and shoot in germany, i did not have a stamp, just gave them a copy of the receipt and they fixed without any issues.
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Old Feb 23, 2010, 7:27 PM   #9
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well thats encouraging =) will contact them and see if they will repair it
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Old Feb 23, 2010, 9:25 PM   #10
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I thought I had answered this thread earlier, but I must have closed the window instead of posting.

My 12-24 significantly front focused on my K-7 - so much so that I thought there was something wrong with it also. It wasn't as bad or as consistent with the K20 so it took me a bit to figure it out - it would not go to infinity on its own. I shot a bunch of focus charts (which is relatively difficult to do with such a wide-angle lens) and could really see it. What surprised me was that even though I thought it was significant, the focus adjust was able to make the appropriate correction.

The lens is sharp, but not DA* sharp. And it's a wide-angle, which means that things in the distance are really in the distance and may lack the detail a 50 mm would. The first picture doesn't show any decentering (at least, in my opinion), you can't tell with the second one as you shot it as a vertical.
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