Workshop 1 - Depth of Field

Workshop 1

Shots 1-6 (below) have the following details of Task, ISO, Aperture, Shutter Speed and Focal Length:

1. shortest focal length - min aperture, 200, f16, 1/20, 18mm
   
   
2. shortest focal length - max aperture, 200, f3.5, 1/400, 18mm
   
   
3. shortest focal length - mid aperture, 200, f10, 1/50, 18mm
   
   
4. longest focal length - min aperture, 200, f16, 1/50, 92mm
   
   
5. longest focal length - max aperture, 200, f5.6, 1/400, 92mm
   
   
6. longest focal length - mid aperture, 200, f10, 1/160, 92mm
   

(All shots use Aperture Priority setting)


Shot 1 (top), shot 2 (middle) and shot 3 (bottom):
(Click on image to enlarge)



Shot 4 (top), shot 5 (middle) and shot 6 (bottom):
(Click on image to enlarge)



In shot #1 (f16) , all the cups are in good focus either side of the focus point at the middle cup. In shot #2 (f3.5), the depth of field (DOF) is somewhat degraded but still comparatively wide at the chosen focal length of 18mm.

In shot #4 (f16), the coins are also in reasonable focus either side of the focus point at the middle coin. However, in shot #5 (f5.6), we can see how the longer focal length of 92mm gives a more dramatic blurring effect further away from the middle coin.

Shots #3 and #6 used a middle aperture of f10 and the resulting DOF appeared to be mid way between the effects obtained at f3.5/5.6 and f16.

In shot #5, I also observed less DOF for the coins closest to the camera compared to the coins placed at the same distance behind the point of focus at the middle coin.

These observations support the conclusion that DOF is wider at a narrow aperture and that this effect is more pronounced the shorter the focal length of the lens.