rays

#1 top of the object, parallel to the axis, strikes the lens, refracts through F
#2
top of the object, passes through the center of the lens unbent
#3 top of the object, aims for F', strikes the lens, refracts parallel to the axis

#1
top of the object, parallel to the axis, strikes the lens, refracts through F (dot in line to F)
#2 top of the object, passes through the center of the lens unbent
#3 top of the object, aims for F', strikes the lens, refracts parallel to the axis (dot back refracted ray)
