Hello friends, today we will discuss Ramdance IPs, its Cardinal points. M doctor is B. Colored Department of Physics, Schrodinger College Convert District, Van Nebert. So, see in this diagram, Ramdance IP is shown, N position of Cardinal points is also shown. So, you will see this position of principal points, even NP2. Now, first principal point lies at a distance alpha from fill lens. So, alpha is d into F1. So, here we have upon F2, D means distance between these two lenses is to F3 and this here is 3 F2 upon F3. So, it is F2 means principal point P1, first principal point P1 lies at a distance alpha 2 from the fill lens. See here, this P1 point lies at a distance alpha 2 from these lens. Now, second principal point P2 lies at a distance beta from the eye lens. So, we calculate beta, beta is equal to minus T in PF upon F1, D is 2 by 3 F means minus 2 by 3 F into this F is 3 F by 4 upon F. So, minus F1 means this second principal point P2 lies at a distance of F by 2. See F by 2 from this eye lens and it is negative because it is towards left side according to sign convention. Now, we will see position of focal points here for the NP. So, first focal point F1 lies at a distance 3 F by 4 from this first principal point P1, see this distance. That is at a distance of F by 4 to the left of fill lens this distance. And second focal point F2 lies at a distance of 3 F by 4 from second principal point P2 this distance. That is at a distance F by 4 behind the eye lens of your from the fill lens. The difference I used for preparation of this focal presentation. Thank you.