Askar FRA400/5.6

Askar FRA400 Versatile Flat-Field Refractive Astrograph Welcome to the Askar FRA Series: The FRA, or "Flat-field Refractive Astrograph," is a state-of-the-art refractive instrument with built-in flat-field correction, perfect for both astrophotography and visual observation. The FRA series stands out in the astronomy market as one of the few versatile and high-quality devices designed for multiple purposes. Advanced Optical Design: The FRA400 features a Petzval-like quintuplet design, incorporating two special ED glass elements. With an aperture of 72mm, a focal length of 400mm, and a focal ratio of f/5.6, this astrograph delivers a 44mm image circle, offering sharp, high-contrast images with excellent chromatic aberration control. High-Precision Mechanicals: Equipped with a retractable dew shield and a 3" rack-and-gear-based high-precision reducer, the FRA400 ensures smooth and accurate focusing. The reducer includes a 360-degree rotator, an M68×1 thread, a 2" adapter ring, and a 1.25" visual adapter, making it a flexible tool for various observing and imaging needs. User-Friendly Back Focus: The FRA400 provides a generous 140mm back focus, starting from the base of the mounting thread to the focal plane. Users can focus on their objectives without worrying about back focus calculations, simplifying the setup process. Stylish and Functional Design: The FRA400 comes with patented multifunctional tube rings, offering practical attachment points on three sides. This design is not only fashionable but also highly functional, providing convenience during observation or imaging sessions. Fast Focal Ratio: The FRA400's native f/5.6 focal ratio is ideal for astrophotography, but for those seeking even faster performance, an optional ultra focal reducer is available, bringing the focal ratio down to an impressive f/3.9. This supports full-frame imaging and significantly reduces exposure time, making it a groundbreaking tool in the field of astrophotography. Simplifying Your Astronomy Experience: The Askar FRA400 is designed to enhance and simplify your observing and imaging practice. Its innovative features and high-quality construction make it an essential tool for astronomers and astrophotographers, delivering infinite surprises as you explore the boundless universe. Specifications FRA400 Parameters Aperture size 72mm Focal length 400mm Focal ratio f/5.6 Objective lens Quintuplet dual ED air-spaced APO Image circle 44mm Back focus 140mm (from the end of rotator M68x1 thread) Overall length 317mm OTA Weight 2.56kg Total Weight (Including tube ring&dovetail plate） 2.88kg Back-end adapter M68×1 male thread, 2" adapter/1.25" adapter Accessories A pair of tube rings, a handle, a dovetail plate, a M68-M48 conical adapter ， an inspection list, a manual Software and Docs FRA400 User's Manual