This was a test shot to see how well miniature Christmas lights would be rendered by the Canon 70-200mm f/2.8 L-IS lens. The lens is at f/2.8,and the lens,despite its rounded iris diaphragm, is rendering point light sources as ellipsoidal shapes. After a few test shots, I determined that the football shaped out of focus highlights did not look pleasing, so I used another lens which I knew had better bokeh. The reason this lens renders OOF highlights as ellipsoidal shapes is due to the rear section of the lens having not a round opening, but a nearly squared rear, mechanical baffle at the back of the lens. The Sigma 30mm f/1.4 also suffers from this problem of mechanical design affecting the lens bokeh. This effect of rendering point sources of light as ellipsoidal or football-shaped blur forms is called the "cat's eye" effect.