An arrangement for adapting the focal plane of an optical system to a non-planar, in particular spherical or spheroidal object, wherein the optical system has a positive total refractive power and generates a real image. The optical system also comprises an optical element with a negative refractive power. Principally useful in all technical fields with the corresponding requirements relating to a curved focal plane, the arrangement is useful in ophthalmologic devices. The eye which is to be examined is the spherical or spheroidal object for example, the front of the eye which has radii of between 5 and 10 mm of small dimensions.