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Two new lenses for Pentax !!
#21
Maybe there are more differences than we think between the Pentax and the Tamron........ or is it just erroneous information at this point in time !!

  According to Ricoh's specs ........ the lens is made or uses magnesium alloy .....

.... yet Tamron's reviewers talk about a plasticy feel !!.... 

...... as yet I struggle to find a clear view of the DAF's front element coatings .... ........ of  the little of what I can see though (a corner) looks fluorine coloured ... rather than the red HD versions.
Dave's clichés
#22
(01-28-2020, 02:08 PM)davidmanze Wrote: Maybe there are more differences than we think between the Pentax and the Tamron........ or is it just erroneous information at this point in time !!

  According to Ricoh's specs ........ the lens is made or uses magnesium alloy .....

.... yet Tamron's reviewers talk about a plasticy feel !!.... 

...... as yet I struggle to find a clear view of the DAF's front element coatings .... ........ of  the little of what I can see though (a corner) looks fluorine coloured ... rather than the red HD versions.

Both Pentax-rebranded Tamron and Tamron use fuorine coatings for the front element, and both state as such on their product pages.
The Tamron for Canon weighs 860 grams. The Tamron for Nikon weighs 850 grams. The Tamron"Pentax" weighs 859 grams.
#23
(01-28-2020, 07:26 AM)Brightcolours Wrote: We do know that the glass is the same. Only you make up that it must have a special Penatx sauce, because "Pentax".

Like I said before, you can't just exchange an element with the same shape element with different light passing properties and expect good results. That you think one has to be "an optical expect" to know that just shows your lack of understanding of anything related to lenses.

What Pentax calls "SP" is the same as others (Canon, Tamron, Nikon for instance) use, and Tamron specifically mentions about this lens. Claiming it must be different because "Pentax" is just silly. And what Pentax' marketing department calls "HD" is their own issue. That they are happy to call Tamron's coatings of this lens "HD" is upto them.

I scaled the Tamron and rebadged "Pentax"Tamron published MTF charts so they match height and width, to make it easier for you to see that the rebadged Tamron is a rebadged Tamron:

[Image: 90BAF9C84ED84E0885CA97C480B4B77D.jpg]

It is a rebadge of a Tamron. Of course it is a customisation for Pentax, just like the Canon and Nikon versions can not be the same, and Pentax has no way of dealing with in lens IS, it is a bit more customised than when you compare the Canon and the Nikon versions.

And even you must be aware of that this is not a PLM lens, right?

And it certainly is not a lie that the Tamron is a better lens (does not shrink to under 135mm at MFD like the Pentax, does not have the CA issues the Pentax has https://www.ephotozine.com/article/penta...view-29351 , and renders a lot nicer).
Yeah, we're having this discussion because I'm a Pentax fanboy and you're not an anti-Pentax troll Rolleyes

Usually it's the third-party makers who are putting as many labels as possible on their lenses.

Yes, an optical expert would be able to say if changing two elements - with the possibility of slightly altering the shape of any elements but not their positioning - could work.
You can not even figure out that it's not about "one element with the same shape".

The MTF graphs were copy-pasted from Tamron. Note that I never claimed improvements in MTF anyway (I'm not claiming anything of this sort, but I guess that's too complex for someone stuck in a "you're saying this because it's Pentax" routine).

Coatings differences can be tested, at least if the coloring is different. Flare resistance is likely improved on the Pentax anyway, because of the added baffle(s).

Of course it's not a PLM lens, but your hypothesis was that Pentax added the focus limiter not because AF speed is something the Tamron is not great at - but because Pentax cameras are slower.
Well, Pentax cameras do benefit greatly from fast AF lenses. Have you ever tried a recent Pentax with the PLM lens?

A lie repeated a thousand times is still a lie. Even if "supported" by convenient selection of 2 criteria and pretending to see more subjective aspects of image quality.
Oh, and that review? You must believe I cannot read - it is praising the Pentax.

(01-28-2020, 02:40 PM)Brightcolours Wrote: Both Pentax-rebranded Tamron and Tamron use fuorine coatings for the front element, and both state as such on their product pages.
I'd guess everyone is using some sort of dirt repelling coating.

Pentax developed their own version, that's why SP is a "Pentax-original". And HD coatings, the secret is in the application method. There are coating-related patents assigned to Ricoh Imaging, this is an ongoing research.

Your point should be limited to the SP/HD labels possibly being reused for the equivalent Tamron coatings. Which would get you to the same point I'm making, that we should try testing this.

(01-28-2020, 02:08 PM)davidmanze Wrote: Maybe there are more differences than we think between the Pentax and the Tamron........ or is it just erroneous information at this point in time !!

  According to Ricoh's specs ........ the lens is made or uses magnesium alloy .....

.... yet Tamron's reviewers talk about a plasticy feel !!.... 
Errors e.g. in copy-pasting are not impossible. Neither is altering the material of some components.
We truly need more information.
#24
LOL. The MTF graphs were copy/pasted from Tamron? It would be logical as this is a Tamron lens. But they are in a Pentax format, not a Tamron format. And the Pentax format MTF curve at the tele end drops off a bit more than the Tamron published one, so what you are trying to say about it being copy/pasted is unclear to me.

So you claim that Pentax "probably" made changes to the design because Pentax wants to point out 1 more "special" glass type than Tamron does, but at the same time you don't want to claim that that will make the lens perform in any way differently?

You claim that "PLM" makes a Pentax combination focus faster/more accurately than with other lenses? Or what is it you claim? So.... This lens has no PLM. And so Pentax cameras will be as ho-hum with it as with other lenses, and slower than for instance a Canon camera with the current Tamron lens. So yeah, that may well be a reason they decided to add the focus limiter. Another reason can be that because it uses the same lens body and has the VC removed, they just added the focus limiter to give the 2nd button a function.

Pentax just calls fluorine coating SP for marketing reasons, not because it is anything different. There are coating related patents "assigned to" ALL lens makers.

That review shows the CA issue the Pentax has, and the Tamron lens does not have. So yeah, that review. Does better CA performance make the Tamron a worse lens?
And I can't think of much that makes a lens worse or better than other lenses than how it actually renders images. The Tamron renders quite a bit nicer, and according to you does that make the Tamron a worse lens? Both lenses are plenty sharp, only one is close to 200mm at MFD. I guess that must make that lens worse?
#25
Web design 101: keep a consistent formatting even when you're quoting someone else.

No, I'm saying that Ricoh Imaging definitely altered and/or asked Tamron to alter the 70-210, and maybe - as suggested by the specs - that includes glass types for certain elements.

I'm not claiming the PLM lens is very fast focusing; it simply is. It feels instant.
Your theory is absurd. The focus limiter was added to improve the lens, and for no other reason.

Everyone has coating-related patents, and everyone claims theirs are original - and they are, in some small - or not so small - way. Is Pentax the only brand which isn't allowed to?

A lens quality evaluation isn't limited to the corner CA. What you're doing is cherry picking.
No, the Tamron does not render nicer.
And the Pentax is the superior lens, no matter what anti-Pentax trolls say.
#26
(01-28-2020, 03:57 PM)Kunzite Wrote: Web design 101: keep a consistent formatting even when you're quoting someone else.

No, I'm saying that Ricoh Imaging definitely altered and/or asked Tamron to alter the 70-210, and maybe - as suggested by the specs - that includes glass types for certain elements.

I'm not claiming the PLM lens is very fast focusing; it simply is. It feels instant.
Your theory is absurd. The focus limiter was added to improve the lens, and for no other reason.

Everyone has coating-related patents, and everyone claims theirs are original - and they are, in some small - or not so small - way. Is Pentax the only brand which isn't allowed to?

A lens quality evaluation isn't limited to the corner CA. What you're doing is cherry picking.
No, the Tamron does not render nicer.
And the Pentax is the superior lens, no matter what anti-Pentax trolls say.

Yes, the Tamron renders nicer. Evidence is clear on that (images). The CA is better, and the lens is actually close to 200mm. So, what besides all that, makes the Pentax have better image quality?
#27
apparently the Tamron has a metal build (plus plastic of course)

   Tamron don't even mention it in their specs ...
Dave's clichés
#28
Speaking strictly about the image quality - better/more pleasing rendering, a more uniform performance, more resilient to flare.

The D FA* is more affected by focus breathing - this is documented on Ricoh Imaging's site as well, directly comparing it with the 70-210 - but this isn't "image quality" per se. Neither is the better macro capabilities of the 70-210.
#29
In my opinion, a lens that does not have the strong negative focus breathing the Pentax has is optically superior in that area. Not about "IQ".
#30
Then you might want to haunt Nikon forums telling people how their Nikkors 70-200 VR II are no good. And to start a petition to redefine "optically superior" as "lack of focus breathing".
  


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