The need of coma at the exit pupil of a telescope for a scanning IR camera is well known. However, in some cases it is impossible to introduce the required pupil coma if there are not enough degrees of freedom. This paper describes the use of a binary surface in a DFOV telescope so that pupil aberrations are properly controlled. The design has been performed on an already existing telescope, maintaining design philosophy. Several positions of the surface are considered. Comparison among all possible configurations is evaluated in terms of image and radiometric quality as well as weight and cost savings. The effect of the binary surface on the system performance over the operative temperature range is also studied.