Originally posted by normhead Are you saying there's any kind of definitive proof that it is?
Even the fact that the lens element diagrams are virtually the same doesn't mean a whole lot. You'd have to confirm the duplication of every element of lens design in each element. Same refractive index in each piece of glass, ground to the same tolerance etc.
Give it up, this isn't civli suit, there are no partial judgements based on probability.
What we suspect is it's a Tamron design based on the diagrams, but even that isn't proof, because we don't know if the refractive indexes, specs and tolerances are the same on every piece of glass. Bring those two diagrams to court and you'll get laughed out of court.As pointed out, we don't even know how much work Tamron does on it's own designs. It's possible they export the manufacture of many components to other companies, which makes the argument even more ridiculous. Even a Tamron in all probability isn't all Tamron.
And for many of us, we just don't even care.
We have a lens to buy, the rest is not important. I don't have to make a decision on it being an off the shelf Tamron or a Pentax manufactured lens. Your need to clarify an issue with speculation and declare the issue settled in your mind shows a certain lack of ability to live with uncertainty.
But I guess you could start a religion where your members have to repeat "The DFA 70-210 is made by Tamron" or get excommunicated. But I'm not joining. It's not an article of faith for me.
It looks the same.
Has the same focal length
The length of the lens is the same
The optical formula is the same
The minimum focusing distance is the same
The maximum magnification is the same and other similarities
Plus as I said, we have two previous data points that say when all the above are true, the lens is made by Tamron on in their factory. That is incredibly relevant, it shows how their business relationships work.
And your facts do you have that says it was made by Pentax? Tamron makes their version in Vietnam so the country of origin is not a point in your favor.
I absolutely have the ability with live with uncertainty. I wrote the following several days ago about Pentax rebadging the lens:
“Does this bother me-no.
In a declining market partnerships are going to be more and more important. Pentax licensing lenses to Tokina, Pentax licensing lenses from Tamron, Tokina licensing from Viltrox, the L mount alliance, etc.
There is no shame in it, it is just the way the world works.”
I just saying you seem be living in denial that the evidence overwhelmingly points in one direction only.
Saying I should believe in something that has no evidence just because something else is not conclusively proven really is logically flawed.
I am done with this conversation, you are free to continue. Normally I live by qui tacet consentire videtur but in this case I am just ceasing because this is tedious and I have better things to do in life.
And this is a friendly forum and your language is getting a bit hostile.