Although this lens has different brand name like Opteka, Rokinon, Bower, Polar and Samyang, they're same lens made in Korea from Samyang Optic. I've purchased one canon mount mail order directly from Korea gmarket. Auto exposure of this lens on my 1D II is not accurate, the images taken are always 2/3 under expose. I must manual compensate 2/3 stop over expose in the camera setting to counter this issue. Image sharpness at center at F2.0 onwards is comparable with my Canon 70-200 F2.8L IS at 85mm F2.8. The colour rendition of 70-200 is more vivid but not by much, this may be due to the better coating technology that Canon applied to their L lens. By the way, this is a very good budget lens consider its price tag that produce image quality comparable to L lens.