It is still an existing lens (EF17-40mmL)! Before using FF camera, I never shot such wide angle view.; U( [8 X! L; T& b9 ?9 P
To me, it is enough to shoot the most wide angle view of scenes.! f! h' c2 b& T
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Sharing own experiences with this lens, I found little difficulty to set a perfect horizontal line. (Constructive problem)& a3 Q* y1 K- [1 O% V4 c$ ]! w
Thus, I guess more difficult to shoot more extra-wide angle (> 93 degree) of scenes when using more super-wide angle or fisheye lens. / r: r, b$ c; C- Y& Q) { 9 v: j6 U6 d* gOf course, you still could say 93 degree = x super wide... 0 E g6 V. C4 b2 t/ _" ]6 N2 NIt would be considered as pure user's view.