Thank you, you must be right, when I use longer focal lengths, like 20mm, 35mm or 90mm, the images align much more smothly, in a grid like of way. What pattern would you chose to shoot with an 8mm fisheye or 10mm. Any tips would be very much welcome at this time.
On my manual Nodal Ninja 5L pano head I would use a pattern of 4-around with a pitch of about +5 degrees with an 8mm fisheye lens on a nikon cropped sensor (DX) body.
For a 10mm fisheye on a Nikon cropped sensor (DX) body I would use one of two patterns. Either 6-around at about -10 degrees pitch plus one-up (or two-up at 180 degrees yaw separation) at about +60 degrees pitch; or indoors I would choose 6-around at approx. -10 degrees pitch and 6-around at approx. +50 degrees pitch.
These patterns all leave a small 'hole' at the nadir about the size of the footprint of my Nodal Ninja 5L pano head rotator. A Merlin mount will have a larger footprint.
There are many alternative ways of handling the nadir 'hole'.