Askar FRA400 Quintuplet Astrograph

Askar FRA400 Quintuplet Astrograph

Welcome to the new Askar FRA series. FRA is the English acronym for “Flat-field Refractive Astrograph”, describing a refractive astrograph with built-in field correction. The FRA series can also be used visually, making it one of the few versatile and high-quality instrument ranges available on the current market.

To ensure easy interchangeability and optical consistency between different configurations, the first model in the series adopts a Petzval-type quintuplet design (including two ED glass elements) with a 72 mm aperture, 400 mm focal length and f/5.6 focal ratio, delivering a 44 mm image circle.

The FRA400 astrograph features a modern optical layout with a retractable dew shield, a rigid 3-inch rack-and-pinion focuser with 360-degree rotator, M68×1 thread, 2-inch adapter and 1.25-inch visual adapter. The focuser includes fine adjustment capability for precise calibration in imaging or observation.

It provides excellent chromatic aberration control and an image quality optimized for a wide range of visual or photographic uses.

The FRA400 also stands out with its patented, stylish and multifunctional tube rings, offering mounting options on three sides, which greatly simplifies imaging or observational setups.

The back focus of the FRA400 is 140 mm, measured from the threaded base to the focal plane. No back-focus calculation is required under normal use: as long as focus is achieved on the target, the system delivers a corrected field.

Compact and versatile, the astrograph accepts a wide variety of accessories, making it an ideal tool for portable observing and sky imaging.

Although f/5.6 is already a fast ratio for astrophotography, a dedicated focal reducer is available, bringing the ratio down to f/3.9. This combination supports full-frame imaging and significantly reduces exposure time, representing an innovation in astronomical imaging.

The mission of the FRA400 is to simplify and enhance observing and imaging experience, opening new possibilities and continuous amazement in deep-sky exploration.

FRA400 Specifications

• Aperture diameter: 72 mm
• Focal length: 400 mm
• Focal ratio: f/5.6
• Objective: quintuplet air-spaced APO with dual ED glass
• Image circle: 44 mm
• Back focus: 140 mm from the end of the M68×1 rotator thread
• Total length: 317 mm
• OTA weight: 2.56 kg
• Total weight with rings and dovetail: 2.88 kg
• Rear adapters: M68×1 male thread, 2-inch adapter and 1.25-inch adapter

Package contents

• Pair of tube rings
• Handle
• Dovetail plate
• M68 to M48 conical adapter
• Inspection sheet
• Manual