Buyers of this lens are fascinated by its most basic characteristic - Aperture. Really - I shot a person at night in the forest, illuminating with a lighter - the aperture ratio drives. When using this lens, you encounter two inconveniences: - A moving trunk that, if the lens is removed from the camera, cannot be screwed back - without voltage on the contacts, there is no reaction to turning the focus ring. - the rear lens is flush with the bayonet, even the contact pad was placed essentially on it. I have never put any other lens on the bayonet with such accuracy. Scary to scratch.