The smallest such spot that a lens can produce is often referred to as the " circle of least confusion ".
2.
We receive, therefore, in no single intercepting plane behind the system, as, for example, a focusing screen, an image of the object point; on the other hand, in each of two planes lines O'and O " are separately formed ( in neighboring planes ellipses are formed ), and in a plane between O'and O " a circle of least confusion.
मोबाइल