hello I want to ask about something and what could be a better place than where experts meet ! i own canon 650D /t4i with a cropped sensor i am interested in portrait photography , and i own 2 lenses : 50mm f1.8 ii and 18-135 stm (which i liked) . the results of my work are sort of fine but only with chest-face photography but when it comes to full-body and groups photography it's unsatisfying with blurred-backgrounds (separation). my question is : i want to buy a general -proposed lens used professionally in all kinds of portrait / weddings . ( a lens that i never switch /not a prime ) may i ask for some suggestions to help me with this matter . thank you . .