I also want to confirm for the mounting rail (aka the one where we have the camera on). I take pano mainly with my 8mm Fish eye and my 10-22 zoom @ 10.
The fisheye I need at about 91mm on that rail, and have enough space for another type of mount. But for the 10mm lens setting, it's completely back, at 107mm on the rail. Would getting the arca mount enable to go far enough back? If not, by how much?