An Academy Award is good — but not great — for business apparently. “Spotlight’’ earned $1.8 million at the box office during the first weekend since winning the Oscar for best picture. To date, director Tom McCarthy’s movie about the Globe series exposing the priest abuse scandal in the Roman Catholic Church has grossed $41 million. “Spotlight’’ was in more than 1,200 theaters this past weekend, which is the most since the movie opened last fall. While it got a bump at the box office because of the Oscar, it wasn’t huge.