Hello aspirant

There are  six cardinal points in combination of thin lenses.

The locations of the six cardinal points of an existing lens may be determined by four means: the nodal slide, the foco-collimator (or swinging collimator), the two-magnifications method, and the use of the Newtonian lens formula

. The cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, Optical system.  Cardinal points help to provide a way to analytically simplify a system with other components.

Hello Krishan,

There are total six cardinal point found in combination of thin lenses which are situated on the optical axis which are defined in such a way so as to facilitate the image formation by the lens system.

Hope it resolves your query.

Good Luck!