Originally Posted by Douglas_of_Sweden 
What is more important to me is this: Those lenses that are produced with identical optical design by Pentax and Tokina, are they Pentax design or Tokina design from the beginning??? You can find people claiming both ways on the web.
You should take a look at patent repository, you will wuickly find what patents belongs to what company.
AFAIK, the DA12-24 and DFA100 is a Tokina design.
The 10-17,16-50, 50-135, DFA50 are Pentax designs.
DA35 I dunno.