Askar FRA600 Quintuplet Astrograph

Askar FRA600 Quintuplet Astrograph

Description

The Askar FRA600 astrograph is based on a Petzval optical design combining a front triplet and a rear doublet, including two ED glass elements. This configuration delivers a high level of apochromatic correction suited to demanding astrophotography applications. Chromatic aberration is effectively controlled while distortion is minimized, ensuring consistent image quality across the entire field.

The FRA600 provides a 66 mm image circle, ensuring well-shaped round stars across the full sensor area. The rear doublet lenses, with a diameter of 80 mm, effectively compensate for decreasing field illumination. Precise manufacturing allows the system to achieve sharpness close to theoretical limits, producing clear and detailed images.

The telescope is equipped with a large 4.2 inch rack-and-gear focuser featuring a 1:10 fine adjustment knob. This design ensures smooth and stable operation even when heavy imaging equipment is attached, without slipping. Multiple connection options are supported, and Askar supplies a standard conical extender with M54x0.75 and M48x0.85 threads for compatibility with a wide range of astrophotography accessories.

Mechanically, the FRA600 features a 125 mm tube diameter and a retractable dew shield. With the dew shield retracted, the total length is only 493 mm, making it a portable 4 inch class astrograph. A set of multifunctional red anodized tube rings provides mounting points on three sides, allowing easy attachment of accessories such as guide scopes.

In addition to wide field astrophotography, the FRA600 is well suited for high quality visual observation. Its excellent chromatic correction and high contrast deliver images comparable to natural visual experience. As a Super APO quintuplet astrograph, it exceeds the performance of standard triplet refractors within the same price range.

Technical specifications

• Type: quintuplet astrograph

• Optical design: Petzval

• Front group: triplet

• Rear group: doublet

• ED glass elements: 2

• Correction: apochromatic

• Image circle: 66 mm

• Rear lens diameter: 80 mm

• Focuser: 4.2 inch rack-and-gear

• Fine adjustment: 1:10

• Supplied threads: M54x0.75,M48x0.85

• Extender: standard conical extender included

• Tube diameter: 125 mm

• Dew shield: retractable

• Length with dew shield retracted: 493 mm

• Tube rings: red anodized multifunctional

• Mounting points: three sides

• Usage: astrophotography and visual observation

This FRA600 Quintuplet Refractor is built on a Petzval design, comprising a front triplet and rear doublet lenses, two pieces of which are ED glass. This combination provides a high level of apochromatic performance for astroimaging.

With wonderful optical design, the FRA600 astrograph provides a 66mm image circle to ensure excellent star shape across the entire field whilst controlling chromatic aberration, minimizing the distortion.

The two lenses in the rear group have a diameter of 80mm, effectively counterbalancing the effect of decreasing field illumination. With the precise manufacturing, they obtain optimal sharpness nearly to the theoretical level, bringing you beautiful clear detailed images with round-shape stars.

The FRA600 comes with a large 4.2" rack-and-gear-based focuser which includes a standard 1:10 focal adjustment knob, the focuser greatly enhances the payload to a pro level, offering smooth operation without slipping when heavy imaging equipment and accessories are attached.

The focuser allows multiple connections. Besides, Askar also offers a standard conical extender with threads of M54×0.75 and M48×0.85 to connect various astrophotographic equipment. 

Mechanically, the FRA600 has a tube diameter of 125mm and a retractable dew-shield. With the dew-shield retracted, the total length is only 493mm, making it a great portable 4" astrograph.

A set of multifunctional red anodized tube rings includes mounting points on three sides, making itself easy for attachment of accessories such as guider scope for backyard viewing.

In addition to supporting wide field astrophotography, the FRA600 is also perfect for high quality observation, providing exquisite chromatic aberration correction and creating images with impressive contrast comparable to visual experience.

The excellent performance would already justify its price if the FRA600 was a mere triplet APO refractor. But our FRA600 is a 4.3" Super APO Quintuplet Astrograph, its ingenuity has already exceeded its counterparts falling in the same price range.