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Pentax 20-40 Limited.

Discussion in 'Pentax Chat' started by Monobod, Oct 30, 2014.

  1. Monobod

    Monobod Phantom of the forum


    Does anyone have any experience of this lens? I have been looking at reports on some of the American forums and there seems to be several reports of samples having de-centred traits. certainly more than one would expect from a quality lens.

    If one gets a lens with this characteristic, how does one see it and can it be corrected, or is it a matter of complaining anf getting a replacement?

    Others have reported softness (not sharp).

    I have decided to sell the K-5 as a kit with the battery pack and Sigma 17-70 lens, but if there are no takers, I may try trading it in for one of these instead. Just don't want to make an expensive mistake.

  2. nimbus

    nimbus Well-Known Member

    I suppose the logical answer is to buy from a retailer who will exchange items without hassle. Many lenses suffer a degree of decentring, the ones we own and think are not as good as they should be! It may well be the case of the difference between average and excellent copies. The forum reports may well include bad users who blame their lens for their own shortcomings.
  3. Done_rundleCams

    Done_rundleCams AP Forum Ambassador to Canada

    "De-centreing traits" ….. what the heck is that?:confused: That's a new one
    to me :eek: which, mind you, shouldn't come as a big surprise to anyone.

    I think I saw on one of the Pentax pages on FB that someone had it (20-40 lens) and had taken some pics with it and, IMS, there wasn't any negative feedback.


  4. Ffolrord

    Ffolrord Well-Known Member

    It seems a bit of an enigma that lens with users reporting rather different, sometimes contradictory experiences. I like the idea of the lens though.
  5. El_Sid

    El_Sid Well-Known Member

    Decentring is the situatation that arise when the optical axes of one or more elements do not align exactly with the others. In mild form the lens by simply blur slightly more at the extremes of the image circle. In more severe cases it can show as parts of the picture being soft or out of focus even when they are clearly in the same focus plane as the subject.

    My first 10-20 Sigma suffered from decentring - one side was sharp while the other decidedly not so, it got replaced...
  6. Monobod

    Monobod Phantom of the forum

    Manufacturing tolerances are sometimes to blame. but one also needs to be aware of the poor workman blaming the tools.
  7. Done_rundleCams

    Done_rundleCams AP Forum Ambassador to Canada

    Ahhhh …. I think :eek: Thanks Nigel :) I believes I am (still) sufficiently fogged :D



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