Ratio 1:3:5:7 Type A-1 On all camouflaged surfaces 1937 – March 1939 (e.g.: Supermarine Spitfire); on fuselage sides 1939 to replacement by type C1, July 1942.  Also used with bright pre-war colours, especially on trainers. The chrome yellow outermost ring on this roundel variation was usually picked up by orthochromatic film in photos as a shade of dark gray, nearly as dark as the central red circle.