depth of field

depth of feild also known as D.O.F :
-F stop
-Aperture
-Focal length
-focus
-DOF
-bokeh

depth of feild dpends on:
-aperture size (F stop)
- focal length (legth of lens)
- distance to subject

F- means focal ratio this can be shown as
       
N=  f/d
F= focal length
D= Aperture diameter
the smaller th eF stop the bigger the hole, the bigger the F stop the smaller the hole.
the bigger the hole the shallower the DOF, the smaller the hole the deeper the DOF

AV on wide aperature (small F stop)
-long focal length (zoom in as much as possible 250mm if you have it)
-as close to the subject as possible
-the subject away  the subject is to the background increase bokeh

deep depth of field:
AV on a narrow aperture ( large F stop)