An example of 8× ratio visible zoom system with mechanic compensator was designed.The focal length and angle of vision of the system were 6.5~52 mm and 6.6°~52°,respectively.The modulation transfer function(MTF) is above 0.6 within the whole focal range at spatial frequency of 75 lp/mm,and approaches the diffraction limit.RMS value of spot diameter was investigated.The cam curves after optimization was given.The system has the advantages of simple structure,high image quality,short zoom path and smooth zoom locus etc.