[Cable40D]

16-35 2.8L and 17-40 4.0L 我都无用过
16-35 贵系因大光圈，同买系F2.8 个时吾够 sharp 系可以理解

如果上述两镜同时用20mm F5.6 边支 sharp D?

Thank you in advance for your comment

[Obi-Wan]

17-40 is sharper from my experience & from the following site:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=412&Camera=453&Sample=0&FLIComp=1&APIComp=2&LensComp=100&CameraComp=453&SampleComp=0&FLI=1&API=3

[Cable40D]

多谢师兄回覆