Originally Posted by Swift1
Only the very first version of the Takumar 28/3.5 is the 7/6 formula with 58mm filter thread.
The 2nd version Super-Takumar and the Super-Multi-Coated Takumar version are both 7/7 with 49mm filter thread.
My mistake, misread the spec sheet. Was looking at the 'late' version of the first version.