Originally posted by funktionsfrei There is evidence. Tamron has licensed the mount specification, as Tamron is the OEM manufacturer of some lenses sold by Pentax (as for instance the 18-250 and the 18-270 or the new 15-30).
There is a known and fairly long-standing collaboration between the two companies, though I don't see that as evidence that Tamron is licensing tech.* Yes, two of the D FA zooms are undoubtedly based on Tamron product as are other lenses in the past. As for the KAF mount...the design patents are long expired. The relationship between Pentax and Tokina in regards to the two DA* lenses is extremely well documented and was well-known and in the press at the time those lenses were released.
There is another AF lens...trying to remember...that was a simple rebadge to Pentax...OK! I remember almost correctly! The 1998 FA 100/3.5 Macro was made by Cosina and sold as Pentax, Cosina, Vivitar, Phoenix, Promaster and probably others. The Pentax version is unique in that the lens is labeled as SMC and assumed to have SMC coatings, but otherwise, it is a Cosina product. Interestingly, the Cosina 100/3.5 Macro identifies in the EXIF with the same code as the Pentax lens...or is it the other way around
Soooo...inquiring minds want to know, did Pentax share SMC and KAF manufacture, design, and functional specs (data api included) with Cosina or were Cosina's standards and reverse engineering "good enough" to satisfy Pentax requirements? Speculation about this lens has come up every once in awhile on this site and strangely enough, exchange of DNA between the two makers appears to have been minimal which is a shame.
Steve
* One can have collaboration and co-production with
NO sharing of proprietary company secrets. For example: an OEM company manufacturers to spec and if part of that spec is to leave space for a chip along with shipping without mount, a lens may be made with zero sharing.