Chatting at the week-end, over lunch on Saturday, with my wife and teenage daughter we got onto the subject of photography. We reminisced about film speeds (ASA100, 200, 400 etc) forgetting to set it on the camera correctly would ruin all the Christmas pictures of Aunt Mabel asleep in the armchair during the Queens speech - having over-indulged - again. We extolled the virtues of aperture settings (f stop) of how to improve depth of field - if this was required – to show the rest of the family having fun at Aunt Mabel’s expense.