A camera that consists of a concave spherical mirror with an aspheric plate situated at the center of curvature of the mirror. The purpose of the plate is to correct the spherical aberration of the mirror. Because the plate and aperture stop are at the center of curvature of the mirror, coma and astigmatism are automatically corrected, leaving only field curvature and a small residual of chromatic aberration to be tolerated. Schmidt cameras cover large fields at apertures of f
/2 or higher.