diff --git a/src/render.c b/src/render.c
index 18690f3..ebae401 100644
--- a/src/render.c
+++ b/src/render.c
@@ -29,13 +29,14 @@ int render(System *system, double **buffer, int pixel_render_max, double pixel_r
   double h = (system->H)*(system->w)/(system->W);
   double tanpsi2 = (system->w)*(system->w)+h*h;
   double cotpsi2 = 1/tanpsi2;
-  double bmax = R0/sqrt(f(R0)*(1+cotpsi2));
+  //double bmax = R0/sqrt(f(R0)*(1+cotpsi2));
+  double rmax = sqrt(tanpsi2);
  
   double *x=NULL;
   double *y = NULL;
   int size;
 
-  init(bmax, chi_rela_err, &size, &x, &y);
+  init(rmax, chi_rela_err, &size, &x, &y);
 
   gsl_interp_accel *acc = gsl_interp_accel_alloc();
   gsl_spline *spline = gsl_spline_alloc(gsl_interp_steffen, size);