These lenses can be supplied either motorised or non-motorised and provide focus tracking throughout their zoom range.
Mark Pontin. Managing Director of Resolve Optics commented “Focus tracking zoom lens offer the benefit that once set up on your camera they will maintain sharp focus throughout the zoom range of the lens”. He added “The mechanical design of a focus tracking zoom lens means that, unlike an electronic zoom lens, they can be routinely used in environments subject to radiation. Also their rugged, stable and highly reliable operating mechanism makes focus tracking zoom lenses perfect for space, aerospace and military applications.