Orthogonal cutting of titanium alloy Ti-6Al-4V was investigated in a series of continuous and interrupted turning tests. Direct observation of the chip formation zone was achieved using a high speed imaging system with a long-distance microscope lens. Frame rates from 20,000 to 50,000 frames per second were used to record the chip formation cycle over a range cutting speeds from 4 to 150 m/min and at feeds of 0.05, 0.075 and 0.1 mm. Strobed laser illumination was used to avoid image blurring. Visual images of the chip formation cycle were synchronised with recording of the cutting and feed forces. Segmented chips were observed throughout the investigation and image analysis of the recorded video sequences allowed the determination of the chip velocity, the shear angle, the segmentation frequency, the critical strain for shear band initiation and the shear strain within the shear bands.