On my notes İ have written that the definition of principle focus is : the point on the principal axes where rays appear to diverge or rays actually converge.
However İ was looking at this diagram of a concave mirror.
The rays do not converge at the principal focus .
So is the definition wrong.
As you can see the rays do not converge at point F (principal focus) which is ironical to the definition.
The image is not formed on the principal focus which from the definition is what should happen. Why is this?
Update.: From the answers given İ understand this now, however İ don't know why lots of websites do not include that it is for parallel rays only.