David, that one looks nearly identical to Quantaray's version of the lens. Where you lettering is orange, mine is white and "Quantaray" in green is where yours labels "Samyang". Otherwise, exact same construction.
The Samyang/Quantaray 70-210 are just about the same profiles (height, diameter) as this " QII " lens. And the lens in question focuses to minimum and macro to a position left of the aperture mark whereas the Quantaray focuses to infinity left of the mark.
I took a walk with the kids to the library today using my "Mystery" 70-210 and the K-7. It goes a little something like this:
The previous three were with saturation, contrast and sharpness set to +3 in camera, nothing else.
These next two are in camera digital filters:
Saturation, contrast and sharpness returned to zero with no edits: