Quote Originally Posted by Destiny View Post
Some web sites say that it's not important that the bubble is level but it does not mention fisheye lenses..
Then I thought, if its not important why put a bubble there in the first place, so it must be important since all pano heads have them....
For a spherical pano, accurate leveling is not important. It can be leveled in the stitcher.
bubbles moves upon rotation because:
1. bubble has high sensitive
2. bubble has inherent error in accuracy
3. tripod/ rotator has some flexibility
4. bubble is not set accurately in factory
5. user error in leveling, eg viewing the bubble at wrong angle.

all this make it impossible for the bubble to stay stationary during rotation.