Geometric Optics Table

Case AKA Can Form
Real Image?		 Can Form
Virtual Image? 		Where q < 0 Orientation
of Real Image		 Sign of f How it looks
Converging
Mirror		 Concave
Mirror		 Y Y back ↓ positive
Diverging
Mirror		 Convex
Mirror		 N Y back NA negative
Converging
Lens		 Convex
Lens		 Y Y front ↓ positive
Diverging
Lens		 Concave
Lens		 N Y front NA negative
Flat
Mirror		 Plane
Mirror		 N Y back NA infinite
Flat
Lens		 Plane
Lens		 N Y front NA infinite

f = focal length
q = image position
front = side of mirror or lens on which object is located
back = side of mirror or lens on which object is not located