The full and reduced shell model calculations have been carried out for the light odd-even 105Sb and 10 Sb isotopes. The model space has been chosen as ld5/2, 0g7/2, ld3/2, 2si/2, and Oh11/2 for the full calculations and excluded 0/iii/2 for the reduced calculations. The reduced shell model calculations of 105Sb and 107Sb isotopes are presented for the first time. We obtain the energy spectra for the 105Sb and 107Sb isotopes in the full and reduced model space by using CD-Bonn two-body effective nucleon-nucleon interaction. The resulting energy spectra are compared to the experimental results to understand the effect of the Oh11/2 level on the shell model calculations. We draw conclusions about the right model space in the shell model calculations for the isotopes around the N = Z = 50 region of the periodic table.