High Shutter Speed

For these pictures I used, the shutter speed changed for what spot I was at. The picture of a water balloon popping in Mr.Phun's hand the shutter speed was 1/640. While the picture I took of a water balloon popping in a student's hand, the shutter speed was 1/1,250. The mode on the camera that I used was manual exposure and was set at continuous shot. The ISO was set at 200 for both of the pictures. I was able to get the water balloon bursting so perfectly because I focused my camera one the jubject, the water balloon. While the student counted out "1,2,3" and at 2 I held the shutter release button down to get these pictures.

Water balloon popping on Mr.Phun.

Water balloon popping on student.