Fast lenses for infrared spectral regions require expensive crystals. Therefore in the lenses of such type the circuits comprising two lenses at a finite distance should be regarded as the simplest circuit. In order to expand the circuit’s correction possibilities for the high quality image, aspherical surfaces are required. The paper suggests the technique for designing such lenses enabling high-quality correction of all monochrome aberrations except distortions and offers guidelines for reducing the chromatic aberrations of position and magnification. An example of calculating a lens with 1:1.2 aperture, 15° angular field and near-diffraction image quality is given.