There are very few placement options for the 16mm Rokinon Prime lens, but once you find the sweet spot, let's go where the rubber meets the mechanism, everything works fine. Not great, okay. If the belt shifts slightly when the lens is rotated and the drive gear is not too tight, slippage will occur and smooth video focusing should be practiced. Overall it's still a great addition to my video kit and will be of great use. There are more issues like balancing when used with Weebills, but patience and practice will improve performance.