The DIY Solution
The pipe clamp as a NPP with a Nikon 10,5 mm hookedn to a Canon 5D
This sound-damped pipe clamp (58-62mm diameter with M8/M10 thread) is about 3.50 euro.
With a suitable M8 and/or M10 screw one can fix a small piece of aluminum at it. This piece of aluminum receives two drillings ( for the distance you have to try out and better you take a slot instead of one of the drillings.)
Fix the clamp into the first drilling or slot and put an equipment screw from under into the second drilling. This screw can be fixed with a second oned from above. The adapter could be used with a fisheye for single-row panoramas right out of the "NO-Parallax POINT".
After using this combination for some weeks now [I'm still excited about the combination Nikon 10.5, Canon 5D (and a pipeclamp)] I want to add an information about a special benefit of this combo.
Once you change the lens, you simultaneously unmount the Adapter. So you can photograph afterwards with other lenses as usual, without fiddling with some additional but unnecessary metal parts at your camera.
And once you remounted the lens, your back in full panomode without the need of attaching an adapter at the cameras body.
If you want to know how to mount and level the "rohrschelle" in an easy way, please visit www.fotoschule-ruhr.de/tipps_14.php. (currently in German only, but a lot of pictures may help to understand the concept without reading.)
The pipe clamp with Nikon 10,5 mm in a sideview