Photography Tutorial - Aperture and F Stops Explained Part 2
Click this link to see assignment number one.

Last week in I showed you what happens when you go from F/1.4 to F/16. You saw me laying in the grass photographing Kermit with a 50mm lens and the Nikon D3s. A few people commented that focal length and distance will effect your depth of field and they are absolutely correct. This was just one example showing you in this situation how the background would be effected by changing your f stops.