Askar FRA600 f/5.6 Quintuplet Astrograph APO Refractor Telescope
The Askar FRA600 is a member of the FRA (Flat-field Refractive Astrograph) series, designed for full-frame astrophotography and refined visual observing. Its 5-element Petzval-like design with two ED elements provides a naturally flat field, excellent colour correction, and crisp, round stars across a generous 66 mm image circle.
Highlights
- 108 mm aperture • 600 mm focal length • f/5.6
- Quintuplet (3+2) APO optical layout with two ED lenses for tight, colour-pure stars
- Native flat field—no external flattener or spacing maths required
- 66 mm image circle—surpasses standard full-frame coverage
- Large 4.2″ rack-and-pinion focuser with 1:10 micro-adjust and multi-thread adapters
- Portable 493 mm length (dew shield retracted), robust rings, handle, Losmandy plate
- Quality-assured mechanical finish and smooth operation under imaging payloads
Customer feedback suggests performance comparable to, or exceeding, some higher-priced alternatives—while remaining practical for portable rigs.
Watch: Unboxing & Demonstration
Optical Design & Field Correction
Like the FRA400, the FRA600 uses a Petzval-style 3+2 configuration: a front triplet (including two ED elements) manages aberrations; a rear doublet sets the focal plane and flattens the field. The 80 mm rear-group elements help maintain illumination, yielding even brightness and pinpoint stars across the frame.
Focuser, Mechanics & Rig-Friendliness
The 4.2″ R&P focuser offers coarse and 1:10 fine control, clear graduations, and multiple thread options. The standard conical extension provides M68×1, M54×0.75 and M48×0.75 connections (with 2″ filter holder), simplifying camera attachment and future-proofing your setup. Multifunction red-anodised tube rings include mounting points on three sides for guidescopes, controllers, and mini PCs.
With a tube diameter of 120 mm and a retractable dew shield, the OTA measures 493 mm retracted, making it a practical choice for travel and remote imaging.
What It’s Great For
- Full-frame deep-sky imaging with a moderate field (nebulae, clusters, smaller galaxies)
- Portable rigs where rigidity, flat field, and simplicity are essential
- High-contrast visual observing with minimal chromatic aberration
Specifications
| Aperture | 108 mm |
| Focal Length | 600 mm |
| Focal Ratio | f/5.6 |
| Optical Layout | Quintuplet dual-ED air-spaced APO (Petzval-like 3+2) |
| Image Circle | 66 mm |
| Back Focus | 160 mm from rotator M90×1 thread |
| Length | 493 mm (dew shield retracted) |
| OTA Weight | ~6.5 kg (TBC) |
| Back-End Threads | M108×1 (no rotator), M90×1; 2″ & 1.25″ eyepiece holders |
| Included Adapters | M90×1→M68×1, M68×1→M54×0.75, M54×0.75→M48×0.75 (with 2″ filter holder) |
What’s in the Box
- FRA600 OTA with retractable dew shield
- Pair of tube rings with top handle
- Losmandy-style dovetail bar
- Conical adapter set (thread converters + 2″ filter holder)
- 2″ to 1.25″ adapter (eyepiece holder)
- Instruction manual & QC inspection list
Gallery
