arca p0 head for levelling + panning
1/4"-20 screw mount was taken off with tube wrench, forced - it was secured with loctite. A standard arca style clamp was mounted using a m6 flat head (sunk) bolt. It would have been more conservative to procure (or make) a countersunk flat head nut for the 1/4" original screw mount. Care must be taken that the clamp knob does not collide with the panning friction+lock (at right).
The clamp was secured against unwanted rotation by fitting a small bolt to the hole provided for this purpose by the p0 head.
A nodal slide is part of the full pano set.