The Askar FRA400 is a dedicated wide-field imaging instrument that combines portability with premium optical performance. Featuring a 72mm aperture and 400mm focal length at f/5.6, this "Flat-Field Refractive Astrograph" is designed to provide discerning astrophotographers with a flat image across a 44mm full-frame circle without the need for additional field flatteners.
At its core is a 5-element (quintuplet) air-spaced optical design, incorporating a Petzval-like rear group and two ED (Extra-low Dispersion) glass elements. This sophisticated layout delivers excellent chromatic correction and fine star sharpness from edge to edge, simplifying the imaging train by removing the need for complex back-focus spacing calculations.
Despite its compact size (just 317mm long), the FRA400 is built for serious work. It features a heavy-duty 3-inch rack-and-pinion focuser with a 360-degree rotator and 1:10 fine focus knob, ensuring precise framing and stability. The included tube rings are multi-faceted, offering mounting points on three sides for easy attachment of accessories.
While natively fast at f/5.6, the FRA400 can be transformed into an ultra-fast f/3.9 system with an optional dedicated reducer. This capability dramatically reduces exposure times, making it a versatile tool for capturing faint nebulosity and large structures in the night sky.
With an OTA weight of just 2.56kg, the FRA400 is exceptionally portable and easy to mount on lightweight trackers or equatorial mounts. It comes complete with tube rings, a handle, and a dovetail plate, ready for your next astrophotography adventure.