Askar FRA is a series of telescopes designed for use in astrophotography, featuring the highest optical and mechanical quality, as well as a built-in field corrector.
The FRA400 400 / 5,6 APO model is a high-class astrograph whose optical system consists of five lenses arranged in two groups. In order to eliminate the phenomenon of chromatic aberration, the manufacturer used in this instrument as many as two lenses made of glass with reduced dispersion, while obtaining high contrast is possible thanks to coating glass surfaces with multilayer anti-reflective coatings.
This device is characterized by a high light of f / 5.6, which can be further increased by using a separately available, dedicated focal length reducer. This structure, both mechanically (solid 3 "hood with a microfocuser) and optically (large diameter circle full illumination) has been optimized for cooperation with cameras and cameras equipped with a matrix full frame.
• an apochromatic quintet with two ED glass elements and a built-in equalizer
• solid cut with 3 "diameter allows to mount even heavy SLRs without fear of loss of alignment
• large diameter of the full illumination disc guarantees coverage of the full frame matrix
• optical system: ED-APO apochromatic quintuplet with air gap
• number of ED glass elements: 2
• Objective diameter: 72 mm
• focal length of the lens: 400 mm
• maximum usable magnification: 144x
• lighted: f / 5.6
• resolving power: 1.66 "
• star range: 11.3 mag
• anti-reflective coating: full multi-layer coating (FMC)
• diameter of full illumination wheel: 44 mm
• built-in field equalizer: yes
• back focus: 140 mm
• diameter of the extractor: 3 ", reduction to 2" and 1.25 "
• type of eyepiece extractor: rack & pinion with 10: 1 microfocus and the possibility of rotation by 360 °
• adapter for connecting the camera or camera: M68x1 - M48x0.75, 63.5 mm long
• length: tubes: 317 mm
• tube diameter: 90 mm
• tube weight: 2.56 kg
• weight with accessories: 2.88 kg
• Askar FRA400 400 / 5.6 APO optical tube
• fastening rings
• carrying handle
• Dovetail footer (Vixen)
• M68 / 2 "eyepiece adapter"
• reduction 2 "/ 1.25"
• M68 / M48 adapter