Askar FRA400 Pro 72mm f/5.6 Quintuplet APO
Welcome to use brand new ASKAR FRA series! The FRA, which stands for “FLATFIELD REFRACTIVE ASTRAGRAPH”, is a refractive astrograph designed for built-in flat field correction. FRA also used in visual observation, this series creates versatile high-quality flat frame images for astrophotography, is the few great telescope of versatile optical tube.
In accordance with the easy conversion of lens parameters, our first FRA series product is the f/5.6 quintuplet astrograph with 400mm focal length and 72mm aperture. Two ED (Extra-low Dispersion) glass elements are also included to effectively suppress chromatic aberration. FRA400 features a 44mm full frame image circle.
Exceptional Image Quality
For easy parameter conversion between different lenses, the first-come of the FRA family features a Petzval-like quintuplet design (two pieces of which are special ED glass) with an aperture of 72mm, a focal length of 400mm and a focal ratio of f/5.6, providing a 44mm image circle.
Advanced Optical Design
The FRA400 quintuplet astrograph has adopted modern optical design with a retractable dew shield, a 3" rack-and-gear-based high-precision reducer containing a 360-degree rotator, M68×1 thread, a 2" adapter ring and a 1.25" visual adapter. The reducer is equipped with fine focal adjustment function for more precise calibration in practical observation or sky imaging.
No Chromatic Aberrations
It’s excellent in controlling and possibly avoiding chromatic aberrations. The image quality is also optimized to satisfy various observing or imaging purposes.
Multifonctional
It’s worth mentioning that FRA 400/5.6 has a pair of fashionable-looking and multifunctional patented tube rings. Various practical attachments are available on three sides of the tube rings which is really a convenience for practical observation or imaging activities.
Portable and Versatile
The portable and versatile astrograph can go with many potential attachments of other accessories during your observation or sky imaging. It’s definitely your intimate helper for your exploration.
Fast Focal Ratio
F/5.6 is a relatively fast focal ratio for astrophotographic use, but we further provide an ultra focal reducer to satisfy the special needs of experienced imagers, greatly reducing the practical focal ratio to f/3.9. This inventive combination supports full-frame imaging and can dramatically shorten the exposure time, which is a pioneering design in the astrophotography field.
