Abstract: A circular knitting machine, a method for controlling textile fabric defects, and a method for retrofitting a circular knitting machine are provided. The circular knitting machine includes a fixed support structure, a rotational support structure, and a system for controlling textile fabric defects. The system includes a digital camera for capturing digital images of knitted textile fabric, a data processor for processing the captured digital images, a camera support structure for holding the camera, and a lighting system to illuminate the knitted textile fabric from the camera side for capture by the digital camera. The camera support structure is fixed to the rotational structure.