Abstract: It is well known that, the synthetic apertures of different shapes are good single a aperture alternative which is used in different optical system to improve its efficiency. However, the issue of the aberration is a considerable challenge. In this research, the optical defocusing error and the spherical aberration of third and fifth order were calculated for circular synthetic apertures system. The evaluated aberration would balance the self-aberration already existed within the optical system which is difficult to reduce it. Therefore, this would lead to a system which is to high extent is free of the aberration. The mathematical calculations were conducted to calculate the value of aberration that balance the intrinsic aberration, the resulted data were acceptable by supposing the number of apertures equal one (single aperture) which agree with previous research.