The lens is designed for full-frame sensor of the Sony Alpha 7 and 7R. The image quality is phenomenal, the 36 megapixel sensor can fully develop its performance with this lens. Since the Sony Alpha 7R at night, in heavy dusk light and fog understandably can not provide reliable sharp over the autofocus, manual adjustment using the lens is facilitated by the fact that the lens on the camera screen feedback on the distance of the focal point are. My tests refer to several hundred photos in adverse conditions in the caves of France. Under bright light, the autofocus of the lens works very precisely.