Askar FRA500 apochromatic refractor

Discover the Askar FRA500

Discover the Askar FRA500, the latest addition to Sharpstar Optics' FRA range, designed to offer astrophotography enthusiasts exceptional image quality in a compact, lightweight format. Thanks to its unique technical features, this astrograph is an ideal choice for outdoor observations and deep-sky photography.

Unrivalled optical performance

The FRA500 offers a focal length of 500 mm with an aperture ratio of f/5.6 and a diameter of 90 mm, enabling optimal light gathering and high-resolution observation of celestial objects. It is particularly noteworthy for its 55 mm corrected image circle, well above the standard 44 mm, which enables distortion-free images to be captured even at the edge of the field - an essential advantage for astrophotography with full-frame sensors. And thanks to its special design, there's no need to calculate the back-focus or add a corrector, making shooting much simpler.

Advanced optical features

• Optical system: APO air-spaced quintuplet (front triplet, rear doublet)
• ED lenses: Includes two ED glass lenses for optimum correction of chromatic aberration.
• Image circle: 55 mm, suitable for full-frame sensors for sharp images right up to the edges.
• Back-focus: 158 mm (from base of M48x0.75 thread on conical extender to focal plane) or 85 mm (from base of M86x1 thread on rotator to focal plane).

Mechanical and ergonomic design

The Askar FRA500 combines sturdiness and aesthetics, with its extendable lens hood decorated with a classic red ring. Its overall length is 452 mm when extended and 410 mm when retracted, and its weight of 4.1 kg makes it easy to transport for outdoor observations.

Physical specifications

• Overall length: 452 mm (410 mm with mist guard retracted)
• OTA weight: 4.1 kg
• Total weight (with Losmandy rings and plate): 5.2 kg

Precision eyepiece holder

The FRA500 is equipped with an ultra-robust 3.5-inch eyepiece holder with dual-speed focusing wheels, offering 1:10 precision adjustment for fine adjustments, essential for astrophotography.

• Focusing wheels: Dual-speed adjustment with 1:10 ratio for fine adjustments.
• Internal scale: Easy to read and precise, facilitating adjustments under observation conditions.

Compatibility and accessories included

The FRA500 is designed for great versatility thanks to its compatibility with many astronomy accessories and its ability to carry guiding or viewfinder accessories :

• Rear thread type: M86x1
• Conical adapter: M48x0.75
• Tube rings: Two sturdy rings with a multifunctional handle for easy transport.
• Losmandy plate: Losmandy style for stable mounting.
• Multiple adapters: For maximum compatibility with your favorite accessories.

Package components

• Askar FRA500 optical tube
• Pair of tube rings with multifunctional handle
• Askar-style Losmandy plate
• Conical expander
• User's manual

Additional features

• 0.7x reducer (optional): For an even shorter focal length and wider field of view.
• Retractable lens: for easy storage and transport.
• Multifunctional handle: for easy transport and tripod mounting.

Conclusion

This model is ideal for amateur astronomers or photographers looking for compact, high-performance, practical equipment. Whether you're a sky traveler or an astrophotography enthusiast in search of the best image quality, the Askar FRA500 will be your ally in capturing the wonders of the sky with precision and simplicity.