Power of an equiconvex lens is given as
P diopters, which relates to its focal length
f by the equation
P=‌.
When this equiconvex lens is divided into two symmetrical halves using a plane that includes the principal axis, each half retains the same focal length
f. As a result, the power of each half-lens remains the same as the original lens, maintaining the relation:
P′=‌‌‌⇒‌‌P′=PTherefore, the ratio of the power of each half to the original lens power is:
‌=1Thus, the ratio of the power of the two halves is
1:1.