In this paper, a review is given about recent problems in binocular design. In particular, the influence of the prism system is discussed and different mounting techniques of prism systems are presented. The effect of antireflection coating of prisms is described. As known since the early 1940s, the rotation of the plane of vibration by total internal reflection at the two roof surfaces causes a loss in resolution and contrast. By a special coating of the roof-edge surfaces this effect can be compensated. MTF-measurements give a quantitative analysis of the effect.