Originally posted by robjmitchell It's educated guess based on the knowledge shared by asahiman combined with my undestanding manufacturing productivity measures. If you are sharing the same optical design its more productive if only one company manufactures the common components. Asahiman has indeed confirmed they are the same optical formulas now, and the lenses will be assembled/made by each company.
There would be some logic it was about Tokina. But mtgmansf posted about the 50mm and Tamron. There's no link whatsoever.
Even about the Tokina/Pentax relation which is, yes, different than with Tamron: AFAIK they always produced their lenses in their own factories but shared the blue print. Nothing else.
Previous collaboration:
Tokina licenced their 12-24 to Pentax.
Pentax licensed: 100/2.8 macro, 35/2.8 macro, 16-50/2.8 and 50-135/2.8 to Tokina (maybe I forgot one but don't think so).
But they separately built everything. Even motors were different.
The current collaboration may include some patens sharing about focus motors.
Dunno if Tokina already had ring type motors ?