To blur or not to blur

Often wrongly considered as a gimmick in street photography, the capability to blur backgrounds (or foregrounds) is to the contrary a wonderful creative tool when...
Often wrongly considered as a gimmick in street photography, the capability to blur backgrounds (or foregrounds) is to the contrary a wonderful creative tool when used appropriately. To illustrate it, let's have a look at two similar pictures taken in Paris by Notre Dame. In both cases, the focus was set on the little girl being portrayed by the painter. An aperture of F4.0 was used in the first frame while the second was taken with an aperture of F1.4 (on the 60mm Konica Hexanon F1.2).  What are the key differences generated by these two different exposure settings ? In...