The corrector lenses range in diameter from 0.85 meters to 1.46 meters, which are smaller than the largest Rubin camera lens (1.55 meters). Notably, all of the lenses are spherical surfaces, which simplifies their manufacture relative to Rubin and DESI which each had several aspherical surfaces. The corrector includes two counter-rotating lenses that act as an atmospheric dispersion corrector (ADC), as was done for DESI. The focal plane is a 0.82-meter diameter surface situated under the primary mirror, allowing easy accessibility. The optical speed at the focal plane is f/3.6 with only a few percent variation, which is perfectly matched to the Spec-S5 spectrographs.
