Yongnuo YN560 - Guide Numbers for Different Focal Length Ranges

Guide Numbers for different focal length ranges (at ISO 100, in meters / feet)
Flash Coverage (mm) Flash
Output
14 24 28 35 50 70 80 105
1/1 15/49.2 28/91.9 30/98.4 39/127.9 42/137.8 50/164 53/173.9 58/190.3
1/2 10.6/34.8 19.8/65 21.2/69.6 27.6/90.7 29.7/97.4 35.4/116.1 37.5/123 41/134.5
1/4 7.5/24.6 14/45.9 15/49.2 19.5/64 21/68.9 25/82 26.5/86.9 29/95.1
1/8 5.3/17.4 9.9/32.5 10.6/34.8 13.7/45.2 14.8/48.6 17.7/58.1 18.7/61.4 20.5/67.3
1/16 3.8/12.5 7/23 7.5/24.6 9.7/32 10.5/34.4 12.5/41 13.3/43.6 14.5/47.6
1/32 2.7/8.9 4.9/16.1 5.3/17.4 6.9/22.7 7.4/24.3 8.8/28.9 9.4/30.8 10.3/33.8
1/64 1.9/6.2 3.5/11.5 3.8/12.5 4.9/16 5.3/17.4 6.3/20.7 6.6/21.7 7.3/24
1/128 1.3/4.3 2.5/8.2 2.7/8.9 3.5/11.4 3.7/12.1 4.4/14.4 4.7/15.4 5.1/16.7