Cornell Capa - Carly Rosenberg

This picture caught my eye because I thought it was fascinating how the dancer's back flip was captured at the perfect moment. Also, the shadows and contrasting colors are captivating. The lines in the photograph seem pretty clear. There is a vertical line down the center where the dancers are. There is also a horizontal line that separates the light floor from the dark background. I believe that the photo was taken with a normal lens due to the fact that the distance between the dancers seems proportional; the person in the background only seems small because she is a child. I also assume that the photographer used a large diaphragm in order to capture the fast-moving dancer.
http://www.magnumphotos.com/C.aspx?VP3=CMS3&VF=MAGO31_10_VForm&ERID=24KL53ZYFH