In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power (p) and magnification (m) for each lens will be, respectively

For a thin convex lens the optical power is defined as

where f is the focal length. When several thin lenses are placed axially in contact, their focal lengths combine such that the total power equals the algebraic sum of the individual powers:

All four lenses are similar, so each has the same power p. Substituting,

Thus the combination’s power is four times the power of a single lens.

The linear magnification m of a thin lens is the ratio of image height to object height. For lenses in contact the overall magnification is the product of the individual magnifications because each lens forms an intermediate image that becomes the object for the next lens:

Since the lenses are identical, each magnification equals m. Therefore

Consequently, the power and the total magnification of the four‑lens system are 4p and m⁴, respectively.