I bought a set of the Rokinon "cine" lenses for my Sony FS100. I unpacked the 35mm T1.5 first and when I checked it out on a product shot I was very impressed. It was as sharp as any lens I have, had excellent contrast and color. But then I started opening it up and it fell apart.
At T1.5 it was way too soft, and the color shifted so the whites had a slight yellowish case. The contrast also changed. At a T2-2.8 it was not as soft but still softer than f4, and the color and contrast still looked funky. Basically it is an F4 lens. Another thing is that when I compared it against my old Nikkor 35mm, which was much sharper wide open and had better color and contrast), the Rokinon was most definitely not 35mm. I didn't do any serious measuring but an educated guess says it's really 40-42mm.
I returned the set (24, 35 and 85) back to B&H and went into debt for more Zeiss glass.
Since then I have read more than one post and had email from another person saying that apparently there is some serious variance in manufacturing. Some people get good copies, some get bad. I obviously had a bad one. If this is true, I guess I could have returned the lens and tried another. However, one other person I know has the 35 and says his is soft when opened beyond F4 too. I didn't check out the 24 and 85, just sent them all back.
It was as big disappointment because I had read so many positive things about these lenses from reputable sources. I did read one lone comment about the color and contrast but ignored it since literally hundreds of posts praised the lenses. I guess it's the luck of the draw. I don't want to come out and condemn these lenses because so many people are happy with them. I'm willing to believe that I got a bad one.