Askar FRA400 72mm F5.6 400mm quintuplet astrograph OTA

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.

It's excellent in controlling and possibly avoiding chromatic aberrations. The image quality is also optimized to satisfy various observing or imaging purposes.

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.  

The ASKAR APO 72 mm f/5.6 quintuplet apochromat from Sharpstar is optimized for astrophotography with high resolution cameras

Specifications

• Aperture 72 mm
• Focal length 400 mm / focal ratio f/5.6
• 5-element quintuplet design with corrector in tube
• Two ED glasses in the objective for very good correction of the chromatic aberration
• 44 mm image circle with full illumination and correction
• 140 mm working distance for visual observation or focal length reduction
• Stable 3" dual-speed RAP focuser with 360° rotation
• 2" and 1.25" receptacles as well as M68x1 external thread for screw adaptations
• Long adapter from M68 to M48x0.75 camera connection is included in delivery (with 2" filterthrad)
• Flexible GP/EQ5 style dovetail bar with photo tripod connection and carrying handle with flexible slotted hole
• Finder shoe for standard finder holder
• Including inspection check list of the manufacturer

The focal ratio of f/5.6 is fast With the optional FRA400 Reducer you can increase the speed from f/5.6 to f/3.9, thus halving the exposure time. The focal length is shortened to 281 mm.