The double-sided telecentric optical zoom system can consist of only three components. Output data of the algorithm include transversal magnification in terminal positions, spaces between components in their start position and the object to image distance. Optical powers are determined from the start position but spaces - from the final position and condition on the object to image distance. In both cases it is necessary to solve the system of three non-linear equations. Afoc-al type of the entire system is taken into account in one equation. Solutions of equations depend on a free parameter val-ue which is the matrix element "b", sometimes called the modified thickness of the optical system. Powers and spaces being determined are functions of the free parameter. This parameter generates many solutions of the optical system, but the designer has to select the most useful one. Important role in the design methodology plays the use of computer graphics for the localization of the free parameter. Recommended solution is such where powers of components aren't too strong and spaces in both terminal positions enable convenient movements of components simultaneously limiting the total length of a system. When the free parameter becomes fixed it is necessary to check the components kinematics. Recommended kinematics should provide for smooth operation from start to final position while keeping the spaces as small as possible. Described methodology of calculations is illustrated by the example.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.