Superb build quality. full metal construction. The optics are impeccable. Rimless sharpness from f/5.6. I usually use this focal length at f/8 or f/11 to get even better results. The colors are rich and pleasantly saturated. The autofocus is as good as any other screw drive lens I've used. Not as fast as SDM, but quite adequate. I usually use this lens in manual focus mode and it's excellent. The ride is smooth and well-damped.