telescopecomparison · 2-way
William Optics Ultra-Cat 131 vs Astro-Physics 110mm f/6 StarFire GTX
William Optics
Ultra-Cat 131
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Astro-Physics
110mm f/6 StarFire GTX
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+19% aperture
Faster by 1.1 f-stops
Specifications
| Specification | William Optics Ultra-Cat 131 | Astro-Physics 110mm f/6 StarFire GTX |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Petzval (5-element advanced) | Apo triplet Super-ED |
| Aperture | 131mm | 110mm |
| Focal length | 648mm | 660mm |
| Native f/ratio | f/4.9 | f/6.0 |
| Image circle | 60mm | 50mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 11.3kg | 5.5kg |
Advantages of William Optics Ultra-Cat 131
- 19% more light-gathering aperture
- Faster optics at f/4.9 vs f/6
- Larger image circle (60mm) — supports bigger sensors
Advantages of Astro-Physics 110mm f/6 StarFire GTX
- Lighter (5.45kg vs 11.3kg) — easier to travel with
Best for — William Optics Ultra-Cat 131
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Best for — Astro-Physics 110mm f/6 StarFire GTX
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics Ultra-Cat 131 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.18° × 2.12°Scale: 1.20"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.08° × 1.39°Scale: 1.20"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.00° × 1.00°Scale: 1.20"/px
Astro-Physics 110mm f/6 StarFire GTX — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.13° × 2.08°Scale: 1.18"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.04° × 1.36°Scale: 1.18"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.98° × 0.98°Scale: 1.18"/px
William Optics Ultra-Cat 131 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Astro-Physics 110mm f/6 StarFire GTX — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
