65PHQ is a flatfield astrograph newly launched after 80PHQ, 107PHQ, and 130PHQ. Instead of buying extra flatteners, calculating the back focus of the flattener, or making a tedious connection to match the correct distance, astrophotographers can simply equip it with any possible imaging accessories, make the target stay at the focus, and then the whole optical system is perfect for imaging.
65PHQ has a smaller size than other PHQ astrographs. 65PHQ has a focal ratio of f/6.4 and a focal length of 416mm. Instead of the quadruplet structure of other PHQs, the 65PHQ is a quintuplet with two ED glasses which offers excellent control of chromatic and other aberrations. With its self-flattening design, 65PHQ offers strong advantages in the astronomical shooting. It supports the full-frame image circle and has a fine spot diagram with tiny distortions of the peripheral stars.
