sound reasonable and I would do it that way if the model was somehow flat. but it has a cube shape (little more complex) and the camera goes around all sides. so there is no general "up". but I could animate the locator around the model as well, you are right. but I can´t use "bank" then, right? and what about the local Y-rotation (if Y is the up vector) it would need to be contrained as well. so this leads to an ell-constraints-solution.

but anyway - thank you for your idea!

any possibilities to fix the motion curve?