In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge [1]. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by aberrations of the imaging optics. In the absence of significant aberrations, the smallest possible blur circle is the Airy disc, which is caused by diffraction from the optical system's aperture. Aberrations tend to get worse as the aperture diameter increases, while the Airy circle is smallest for large apertures.
But if you meant focusing then....
"Focusing" has been referred to as "a procedure for attending to, and being aware of, the body's 'knowing' of the various situations we live in." This way of describing Focusing can be misleading. It's perhaps more accurate to say that Focusing is what you are doing, any time you pay attention to the feel or quality of what you mean and enter into the murky, unclear "edge" of "all that", opening it up by the use of different kinds of questions or suggestions and describing what you find in words, images or actions.
Because we are interacting with a universe which is more intricate than our concepts, we have an implicit knowing "in the areas in which we interact", which is more than our concepts.
Focusing is not a technique, but a naturally occurring human process. When we are focusing, we are intending to establish an interaction between our rational understanding and our somatically rooted “knowing”.
See it's simple
