Low depth of field (blurry back ground) is created by;
Long focal length + wide aperture + fast shutter speed (200MM, f2.8, 2000th sec @ 200 ISO)
High depth of field (crisp image throughout) is created by;
Shorter focal length + narrow aperture + slower shutter speed (50 mm, f11, 125th sec @ 200 ISO)
Hope that helps
