摄影技术的普及及审美情趣的提高，使摄影者对器材及技术的要求越来越高，人们往往倾向于运用独特的、超常的视角来提高画面的表现力。因而越来越多的摄影者在选购照相机镜头时，开始向更广角和更长焦距的方向发展。前些年，镜头焦距小于24mm和焦距长于210rum的镜头市场均为进 With the popularization of photography and the improvement of aesthetic taste, photographers are demanding more and more equipment and technologies. People often tend to use unique and extraordinary perspectives to enhance the expressiveness of the images. Therefore, more and more photographers in the purchase of the camera lens, began to wider angle and longer focal length direction. A few years ago, the lens focal length is less than 24mm and focal length longer than 210rum lens market are into