The 8mm fisheye, mounted vertically and using only horizontal shots, produces 360x180° panoramas without much hassle. Many panoramas are workable using only Hugin's automated settings (turn on rotation search in preferences). Adding zenith/nadir shots tends to increase likelihood of errors and necessitates manual control points. Producing quality stereographic projections requires careful use of zenith/nadir shots or outer edges will suffer from heavy interpolation artifacts.
Further testing is necessary to determine if the zenith/nadir shots can be force-stitched into the panorama. Perhaps crop upper edges of horizontal shots?
Further testing is necessary to determine number of shots for 360x180° panorama from 12-24mm. Stereographic projections should have clearer edges with this setup.
Note: Plate settings are preliminary.
D2x with Kirk Enterprises L-bracket.
PG-02 Ultimate-Pro Omni-Pivot
Sigma 8mm f/4 EX
Horizontal
CB-10: 8
PG-02 VA: 4 inside edge
MPR-CL II: 6
Row middle: 270° + 90° stops = 4 shots
Row up/down: 225° + 90° stops / 315° + 90° stops = 8 shots
Zenith/nadir: 0° + 1 / 180° + 1 = 2 shots
Vertical
CB-10: 8
PG-02 VA: Between 10 and 5
MPR-CL II: 9.2
Row middle: 270° + 45° stops = 8 shots
Zenith/nadir: 0° +1 / 180° + 1 = 2 shots
Tokina 12-24mm f/4 ATX (12mm)
Horizontal
CB-10: 8
PG-02 VA: 4 inside edge
MPR-CL II: 7.6
Row middle: 270° + 45° stops = 8 shots
Row up/down: 225° + 45° stops / 315° + 45° stops = 16 shots
Zenith/nadir: 0° + 1 / 180° + 1
AF-S Nikkor 18-70 f/3.5-4.5 DX (18mm)
Vertical
CB-10: 8
PG-02 VA: Just under 10 outside edge
MPR-CL II: 9