130PHQ APO Quadruplet Astrograph

The 130PHQ is a long-focal-ratio, flatfield astrograph featuring 130mm aperture with a focal length of 1000mm and focal ratio of f/7.7. The refractor uses a quadruplet air-spaced optical configuration with two ED glass elements to reduce chromatic and other aberrations. It supports a 60mm medium format image circle with fine spot diagrams and central RMS radius less than 2 microns, making it ideal for both wide-field deep sky imaging and high-magnification lunar and planetary observation. The built-in field flattener eliminates the need for back focus calculations or additional field flattener accessories.