The main focus of the collecting lens is the point on the main optical axis at which all rays are collected, falling on the collecting lens parallel to its main optical axis. The main focus of a scattering lens is a point on the main optical axis at which the extensions of rays incident on the scattering lens parallel to its main optical axis are collected.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.