This paper presents a guideline to aid the space group determination of distorted perovskites by a combination of properties, selected area (SAED) and convergent beam electron diffraction (CBED). The case study reported here is based on the (Pb,Ca)TiO3 pseubinary-system. This material represents a combination of polar compound without inversion point (PbTiO3) and incipient-ferroelectric with octahedral tilting (CaTiO3). The practical aspects of each guideline step are: 1) Glazer tilt system determination; 2) lattice type determination; 3) indexing of the diffraction group; 4) point group determination by CBED, optionally combined with analysis of the group-subgroup relationship of the phase diagram compounds and/or the physical properties; 5) observation of the symmetry of systematic absent spots (G-M lines); and 6) matching of the G-M symmetries with the space group possibilities. This work highlights the use of the presented set of characterization to make possible the space group analysis for perovskite polycrystals with tiny distortion.