Askar FRA500 500/5,6 APO fi 90 mm

Askar FRA is a remarkable series of professional refractors meticulously designed for astrophotography, boasting unrivaled optical and mechanical quality.

One standout member of this series is the Askar FRA500 500/5.6 APO, an exceptional astrograph featuring a sophisticated optical system comprised of two lens groups housing a total of five lenses. To tackle chromatic aberration head-on, the manufacturer incorporated two lenses crafted from low-dispersion glass. Additionally, the lens surfaces are coated with high-performance multilayer anti-reflective coatings, ensuring optimal contrast for breathtaking astrophotography.

Both mechanically and optically, the Askar FRA500 500/5.6 APO has been expertly optimized for seamless compatibility with full-frame cameras and imaging devices, exemplified by its sturdy 3.5-inch rack & pinion focuser with a microfocus mechanism and a large diameter fully illuminated circle.

Key Features of the Askar FRA500 500/5.6 APO Optical Tube:

• Apochromatic quintuplet design incorporating two ED glass elements
• 3.5" rack & pinion focuser facilitating precise alignment even with heavy loads
• Ample 55mm diameter of the fully illuminated circle, ensuring full-frame sensor coverage

Technical Specifications:

• Optical system: ED-APO apochromatic quintuplet with air gap
• Number of ED glass elements: 2
• Objective diameter: 90mm
• Lens focal length: 500mm
• Aperture ratio: f/5.6
• Anti-reflective coating: Full multi-layer coating (FMC)
• Diameter of fully illuminated circle: 55mm
• Back focus: 158mm from the M48x0.75 thread on the conical adapter end / 86mm from the M86x1 thread on the focuser rotator
• Focuser diameter: 3.5"
• Focuser type: Rack & pinion with 10:1 microfocus and 360° rotation capability
• Camera or imaging device connection threads: M86x1 / M48x0.75
• Mounting foot: Losmandy
• Tube length (with extended dew shield): 452mm
• Tube length (with retracted dew shield): 410mm
• Stem/tube diameter: 120/105mm
• Tube weight: 4.1kg

Included Components:

• Askar FRA500 500/5.6 APO optical tube
• Mounting rings
• Carrying handle
• Losmandy mounting foot
• Conical adapter
• Documentation

Warranty:

The Askar FRA500 500/5.6 APO comes with a 24-month warranty, ensuring your peace of mind and satisfaction with this extraordinary astrophotography tool.