sorry I have come to this discussion a tad late.

I already have a R1 with 8mm and 10.5mm ring with a nadir adapter.
I was wondering what my options would be to get a complete spherical pano on a pole.
I don't know how both the zenith or the nadir would be covered given that the nadir adapter would be totally useless on the pole.
Im using a D300 with 8mm and 10.5 for panos.

My preference would be for 10.5 before the 8mm
all suggestions are most welcome.