telescopecomparison · 2-way
Askar FRA600 vs William Optics Ultra-Cat 108
Askar
FRA600
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics
Ultra-Cat 108
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+16% focal length
Slower by 0.8 f-stops
Specifications
| Specification | Askar FRA600 | William Optics Ultra-Cat 108 |
|---|---|---|
| Optics | ||
| Type | Refractor | refractor |
| Optical design | Petzval Quintuplet APO | Petzval (5-element advanced) |
| Aperture | 108mm | 108mm |
| Focal length | 600mm | 518mm |
| Native f/ratio | f/5.6 | f/4.8 |
| Image circle | 60mm | 60mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 7.8kg | 8.0kg |
Advantages of Askar FRA600
- Tighter framing — 600mm vs 518mm focal length
Advantages of William Optics Ultra-Cat 108
- Wider field — 518mm vs 600mm focal length
- Faster optics at f/4.8 vs f/5.6
Best for — Askar FRA600
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — William Optics Ultra-Cat 108
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Askar FRA600 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.44° × 2.29°Scale: 1.29"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.24° × 1.50°Scale: 1.29"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.08° × 1.08°Scale: 1.29"/px
William Optics Ultra-Cat 108 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.98° × 2.65°Scale: 1.50"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.60° × 1.74°Scale: 1.50"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.25° × 1.25°Scale: 1.50"/px
Askar FRA600 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics Ultra-Cat 108 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
