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适马17-70mm f/2.8-4.5 DC Macro镜头这只镜头专用于APS-C数字单反相机,相当于35mm相机的25.5-105mm镜头,接近于28-105mm,这是一个非常常用的焦段。镜头对焦动作的旋转角度只有55°,有助于提高AF速度,使AF声音短暂。手动对焦的手感很轻,也很精确。在对焦过程中,镜头的前面不旋转,镜筒也不延伸。滤镜直径为72mm,不建议套用两个及以上的滤镜。变焦运动是镜筒两节延伸。镜头标注了在最近对焦距离时的影像放大倍率,在17mm时为1:4.7,即影像为被摄体大小的1/4.7;在70mm时为1:2.3。
Sigma 17-70mm f / 2.8-4.5 DC Macro Lens Designed for APS-C digital SLR cameras, this lens is equivalent to a 25.5-105mm lens for a 35mm camera, which is close to 28-105mm and is a very popular focal length. The focus of the lens rotation angle of only 55 °, help to improve AF speed, AF sound short. Manual focus feel very light, very accurate. During focusing, the front of the lens does not rotate and the barrel does not extend. The filter diameter is 72mm. It is not recommended to apply two or more filters. Zoom movement is the tube two sections extend. The lens captures the image magnification at the closest focusing distance, 1: 4.7 at 17mm, 1 / 4.7 of the subject’s image size, and 1: 2.3 at 70mm.