Except the slight corner dullness wide open, this lens is tremendously sharp. Since there is enough light in the corners considering the angle of view and the distortion is minimal, this is a great lens for architectural photography. Of course, I use this dynamic 98-degree angle of view when I need it, but I can also shoot bold street shots because the perspective is natural even when I look up. Many ultra wide angle lenses show overemphasized and unnatural perspective if the camera isn’t kept level with the horizon and perpendicular. Because of this difficulty, it’s common that these ultra wide angle lenses become a permanent resident in the camera cabinet. But this lens doesn’t present such difficulty – it just shows the natural perspective. So, I strongly recommend this lens to those who are reluctant in using ultra wide angle lenses. Take courage and enjoy the dynamic world.