Does anyone know the minimum number of images for a full 360° VR pano. with the Samyang 7.5mm fish ? Is it possible to make do with 5 images - that's four around, angled down just enough to cover the nadir, and then one zenith shot ?
Probably far too late to be of any use to you, but yes, you can do it with five shots like that. Angle down by 30°, four around in portrait orientation at 90° yaw rotation, and a zenith shot will cover the sphere. But it's tight. It took me two or three tries to get it right my first try and I was just freely handholding: no plumblines or anything. You have 130° coverage across the frame.