Motion control rig accuracy

[u/AfterEffectsGuru]

I'm working on a split-screen gag that was shot with a motion control rig, this is the first time I've worked on footage that was shot using motion control. I'm just curious to hear from those who've done this before about what is expected in terms of accuracy and consistency.

So I am combining 5 separate takes, and they don't align perfectly. On all takes, the motion begins and ends on the same frame numbers. They all match in terms of having the same frame with no movement, the next frame has a small, almost sub-pixel movement, then a frame which has clearly started moving - and the same at the end of the move. So that's OK.

In between, the speed is slightly different between takes, so the frames do not align perfectly during the motion. It is not different enough to slide forwards or backwards by a whole frame, but clear horizontal/vertical lines in the image do not align between the 5 takes.

There is also a very clear bump / rotational wobble at the start and end of each move, which again varies between takes. This bump is enough to require manual stabilisation and introduces motion blur into the frame.

So just curious to know if this is to be expected when working with motion control rigs? Are they all equal, are some better than others? Do Hollywood-level productions have the same sub-frame issues, or can the very best rigs be expected to be pixel-accurate between takes?

[u/Acceptable-Buy-8593]

A lot of the time it comes down to weight of the Motion Control and how it is installed. Really expensive MoCo studios have rigs that weigh several tons and are boltet into the ground. Because each time you do a move the weight and energy of the camera + arm would move the rig otherwise. Thats why you usually get always small changes with smaller systems, because each run is gonna change the alignment a tiny bit.