Because of the 40/2.8 I have decided to not get the 35/1.4 II anymore.
At Building Panoramics we actually chose to use the 40 STM rather than the 35 f1.4L for our latest picture which is a panoramic of the beautiful interior of Beverley Minster in England.
We used the 40mm for a number of reasons. Firstly the focal length fitted what we were shooting, but also the shallow nodal point makes movement of the camera in a 5 across two up panoramic stitch easier to manage and we don't need to use the sliding panoramic head. ( JVLphoto pointed this out in his response ) . Also we always shoot at f8, and at this aperture the 40 is just as good as the 35 L. And lastly the 40 has virtually zero distortion.
Sophisticated stitching programs can tolerate a great deal of distortion, but using a lens that has virtually zero distortion to start with makes putting the picture together a lot easier. For anyone who wants to shoot panoramics but doesn't have sophisticated stitching programs - get this lens !
The "focus by wire' is growing on me. To start with I appreciated the smoothness of the ring but found the total lack of connection to anything a little off putting. However I'm getting used to it, and think in time I will prefer it to the really - well errr - crappy manual focus on the other cheaper Canon lenses - meaning 50 1.4. Canon please improve this on the new 50 IS