S-curves and spirals

I took my photo tour group to the Queen's House in Greenwich, England specifically to photograph one of my favorite staircases in Europe. The Tulip Staircase dates from the 17th century, and for this composition I used a 16-35mm wide angle lens set to the 16mm focal length. The railing is actually black, but because I shot this with tungsten white balance, it went blue which is what I wanted. My settings were 1/40, f/11, and 3200 ISO. I focused to a point about 5 1/2 feet into the frame for maximum depth of field. My formula for determining this is to convert the focal length of the lens from millimeters to feet and then divide by 3 (i.e. 16mm divided by 3 = 5.3 feet), and that is the distance that produces the maximum DOF. This technique only works with wide angle lenses.