The Takahashi BRC-250 is of Baker Ritchey Chrétien design. It incorporates an oversized hyperbolic primary and auxiliary lenses to achieve a flat field with perfect star images. Spherical aberration, coma and astigmatism are also greatly reduced. It has a fast focal ratio of F/5 allows faint objects to be photographed at relatively short exposures. Image circle is an incredible 100mm allowing use of formats up to 4x5s. Photographic field of 5 degrees allows framing of the widest field objects such as M31 and M45.