The paper presents the X-ray Multi-Foil Optical (MFO) system proposed for the CubeSat demonstrator. The Lobster Eye (LE) design represents wide field of view (FOV) X-ray optics. This feature is unique in comparison with classical Wolter types of X-ray optics that reaches a field of view of typically 1 degree or less. LE optics can theoretically achieve an unlimited field of view, but for practical reasons, modules with, for example, 6 deg x 6 deg large FOV can be designed, developed, and constructed. Presented theoretical study of the Multi-Foil wide-field X-ray “Lobster eye” based optics shows effects of focal length, foil spacing and reflective surface (Au versus Ir). The main parameters that have been compared are effective area, gain, FWHM and/or transmission. The system can be used as an all‐sky monitor in future projects.