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01-03-2008, 08:47 AM   #31
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QuoteOriginally posted by nosnoop Quote
Pentax's diagram is a low resolution one, and that's why some subtle details are not very clear.
I agree, as pointed out in post #25


QuoteOriginally posted by nosnoop Quote
But the elements shapes and number and placing of ED/AS elements are identical
Well from these diagrams I honestly would not dare to conclude that the shapes of the (hybrid) AS elements are the same, nor would I dare to conclude that they are different. I see difference in these diagrams, which could indeed be down to an inaccurate representation or a difference in design, I have no clue.

To me it is simple or the diagrams are accurate and one can draw conclusions on the shapes in the diagrams, or they are inaccurate and one could not draw conclusions on the shapes of the elements.

QuoteOriginally posted by nosnoop Quote
(which disproves the theory that the two versions are fundamentally different in the number of ED/AS elements). And this is no prototypes, these are final official drawing of the elements representation.
Yes, I'm inclined to agree with you on that (didn't state otherwise).


QuoteOriginally posted by nosnoop Quote
And if one trusts the words of "workers" more than the official printed material, what can I say?
Personally I only (somewhat) trust an official Pentax or Tamron statement, but why trust a low "resolution diagram" with "not very clear details" to the point where you can't even say with 100% certainty it is identical?


Last edited by CSpronken; 01-03-2008 at 08:55 AM.
01-03-2008, 09:36 AM   #32
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QuoteOriginally posted by nosnoop Quote
Pentax's diagram is a low resolution one, and that's why some subtle details are not very clear. But the elements shapes and number and placing of ED/AS elements are identical (which disproves the theory that the two versions are fundamentally different in the number of ED/AS elements). And this is no prototypes, these are final official drawing of the elements representation.

ED is the same as LD, just different terms used by different manufacturers.

And if one trusts the words of "workers" more than the official printed material, what can I say?
Maybe you should read the bottom of that diagram where at * and triangle are. It states all pictures and diagrams are from the prototype version and are subject to change without warning or notice. Trust me you are wrong, I'm sorry, but you are wrong is saying they are exactly the same. My creditable people include the current president of Pentax USA and you can't fool all of us.
01-03-2008, 10:14 AM   #33
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Yes it does say the specs could be changed, but you can't just put/take glass from a lens like this. Every minor change alters the optics, I doubt Pentax would have changed anything just for the sake of it, as both models are reported to have exactly same characteristics. And both are reported everywhere they are sold as having 16 elements in 13 groups. The Tamron is also reported on every site as having two ED, two AL and one AD element.

Seriously, I appreciate info brought to us by guys like you, but I still don't get the point on this kind of discussion. You don't need to prove you have insiders telling you all the secrets, this is no secret, the specs are all over the web for all to see. Unless all the reviewers and sellers are badly mis-informed. I don't mean to offend you, but come on. Maybe what they meant to you is that pentax makes some glass but following the tamron design specs, It would still be the same lens.
01-03-2008, 11:46 AM   #34
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Pardon me. but no one has claimed the lenses to be fundamentally different

I've just found a source providing information indicating there are greater differenses than what we have been assuming.

Tim

EDIT: Corrected typos


Last edited by Fototim; 01-03-2008 at 11:59 AM.
01-03-2008, 11:52 AM   #35
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QuoteOriginally posted by Fototim Quote
Pardon me. but no one has claimed the lenses to be fundamentally different
codiac2600 claimed that the number of ED/AS elements are different - and optically, that's a huge difference. And you cannot change that without a fundamental redesign.
01-03-2008, 12:01 PM   #36
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QuoteOriginally posted by nosnoop Quote
codiac2600 claimed that the number of ED/AS elements are different - and optically, that's a huge difference. And you cannot change that without a fundamental redesign.
You are right, he did.
01-04-2008, 09:14 AM   #37
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QuoteOriginally posted by nosnoop Quote
Basically the Pentax 18-250 version appeared out of the blue. And you can see that it is identical to Tamron's design right down to the lens cap.
I'm now the happy owner of the DA18-250 and a DA*50-135. The light is no good, so I haven't tested them yet. Except playing a bit with them. First impresion is good on both. Both seem well built, and zoom and fokus is smooth. Off cource they really can't compare. But all things concidered tha DA impresses me too.
Ooh, I feel enabled

But here is the point of this post: I could swear that the lens caps on them are identical, except for the size. In other words. The lens cap part of your argument does not stand.
After introducing the DA18-250 Pentax has switched caps design to Tamron style caps. A much better design than the old one BTW.

This does not proof anything either, off cource. Probably we will never know.
I'm just reporting.

Tim
01-04-2008, 11:34 AM   #38
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QuoteOriginally posted by Fototim Quote
But here is the point of this post: I could swear that the lens caps on them are identical, except for the size. In other words. The lens cap part of your argument does not stand.
After introducing the DA18-250 Pentax has switched caps design to Tamron style caps. A much better design than the old one BTW.
That's interesting, I did not know that.
The 18-250 is still missing some of the other Pentax "signature" features such as the polarizer window in the lens hood and the Quick Shift clutch mechanism. Doesn't prove anything, just an observation.

01-04-2008, 11:47 AM   #39
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QuoteOriginally posted by nosnoop Quote
That's interesting, I did not know that.
The 18-250 is still missing some of the other Pentax "signature" features such as the polarizer window in the lens hood and the Quick Shift clutch mechanism. Doesn't prove anything, just an observation.
Valid points Nosnoop.

I've been playing a bit more with them now, and I know one thing for sure. I will miss the QS feature on the 18-250. Specially when zoomed in, it tends to need a helping hand in low light situations. And it is a PITA to turn off AF to do that.

Tim

EDIT: Deleted one sentense.
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