Based on the importance of the short range order effect of the plasmas OCP, which is expressed through the damped oscillations of the pair correlationfunction g(r), The authors carry out elaborate examinations of the location rmax as well as of the amplitude gmax of its first maximum for various values of the screening parameter and put forward for the first time the analytical formulae for these data. The linear variation of the screening potential for some interionic distance can be therefore explained thoroughly by considering the relation between this first maximum and the screening potential. Especially, using this accurate fit of gmax established for dense OCP plasmas, the article expand it to the region of weakly correlated ones and point out the value Tc of the correlation parameter for which there exists the onset of the short range order effect. This value is very close to ones proposed in other works.