Originally posted by tibbitts Yes but there are many reports of decentered Pentax lenses too - and not just from me (not that I haven't been responsible for quite a few.)
My only decentered lenses are the Sigma 18-250, and the Tamron 17-50, both have which have become un-useable. Meanwhile my original DC motor purchase my 18-135, also my most used lens, just keeps chugging along. Even my older cheap plastic construction lenses still do well. The problem with keeping stats on decentered lenses, is, we have no way of knowing if they were dropped, or in other ways physically impacted. People can swear on a stack of bibles that they were never physically abused, but we don't really know. My DA 18-135 was bought for use on a K20D back when it was the flagship, and it's been lugged all over Algonquin Park.
No one ever said Pentax lenses would stand up to anything they can be subjected to. But from my experience, they hold up better than third party brands. The insinuation that there should be lenses that can stand up to any potential abuse is misleading. People can ruin lenses. But with my Sigma 18-250 and Tamron 17-50, they didn't stand up to the every day use we demand of our lenses. All of our Pentax branded lenses have.
So does one guy claiming he has a lot of Pentax lenses that are decentered mean anything?
I have three questions
Are your testing methods more critical than most peoples? (really critical because in my mind decentered means the lens ruins images taken they way I shoot them, it's not a lab test. If it's not ruining my images I could care less if someone else claims they are decentered.)
Are you shooting wide open with fast lenses, where decentering is going to be more critical than for ƒ8 shooters?
What physical wear are you subjecting those lenses to?
My experience would say it's one of those three or a combination of those three factors..
But that Pentax has problem with lenses becoming decentered is not supported by my experience.
And in no universe would I ever expect no Pentax lenses to ever become decentered. It's about the likely hood of such a thing happening. Unless you're saying Pentax lenses become decentered more than third party lenses or the competitions lenses, I'm not even sure what your point is. And if you think that, I certainly want to know why you think that.
Start with my data....
3 Tamron Lenses - 1 decentered. 66% keeper rate.
4 Sigma lenses, 1 decentered, one failed internally without reason. 50% keeper rate.
15 Pentax lenses - all functional. 2 broken by serious drops. 100% keeper rate without known physical abuse.
With my most used and abused lens ever, the DA 18-135 still functioning perfectly after all these years.
I wonder what kind of difference it would make adding your list of failure to mine. How much would change?
I certainly wonder how as someone who makes full use of Pentax durability, one person could have so many decentered lenses.
And I'd certainly suggest you don't make this kind of statement without some back ground. People like me don't evaluate posters, although some have earned excellent reputations, we evaluate numbers. After all I don't know you from Deputy Dawg.
All I know from your post is some guy says he has a lot of decentered Pentax lenses.
I don't know the "some guy" and I have no idea what his claims actually mean. He could be rock solid, he could be a total flake.
But given my own experience you know which way I'm leaning.