Originally posted by house It would be quite strange Tokina copying a wide angle zoom from Pentax. Pentax being the brand without wides and Tokina being regarded as the wide zoom specialist! In this case I would completely understand the assumption of the inverse relationship.
Yet the patent request corresponding to the optical formula of the HD Pentax-DA★ 11-18mm f/2.8 ED DC AW was filed (JP,2016-239192) on the 9th of December, 2016 by
Ricoh and published (JP,2018-097053,A) on the 21st of June, 2018.
The name of the inventor is Takahiko Oishi. He is also one of the inventors of a patented but not released 4.2mm f/1.8 lens for the Q system. The corresponding patent request was filed in June 2014 and published in January 2016 (JP,2016-004093,A).