Zeiss Mark-VI was presented in 1968, just one year after the previous model. The projector has a weight of 2.5 tons. It is characterised by significantly improved star images. A new arc lamp is capable of 1350 W; it has to be exchanged after 1500 hours of service. A new optical system makes the stars to shine point-like, clearer in colour and - they scintillate. The rising and setting of the sun becomes more realistical: It has got a red hue close to the horizon. Several other features are adopted from Mark-V like the eclipse projector, coordinate grids and constellation figures. Another impressive thing is the low-noise operation of the motors. The variable step motor has become a standard for any motions in the sky. The functionality was so intriguing that no other model would be developed for the next 20 years.