telescopecomparison · 2-way
Astro-Physics 110mm f/6 StarFire GTX vs William Optics Ultra-Cat 108
Astro-Physics
110mm f/6 StarFire GTX
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
+27% focal length
Slower by 1.2 f-stops
Specifications
| Specification | Astro-Physics 110mm f/6 StarFire GTX | William Optics Ultra-Cat 108 |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Apo triplet Super-ED | Petzval (5-element advanced) |
| Aperture | 110mm | 108mm |
| Focal length | 660mm | 518mm |
| Native f/ratio | f/6.0 | f/4.8 |
| Image circle | 50mm | 60mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 5.5kg | 8.0kg |
Advantages of Astro-Physics 110mm f/6 StarFire GTX
- Tighter framing — 660mm vs 518mm focal length
- Lighter (5.45kg vs 7.96kg) — easier to travel with
Advantages of William Optics Ultra-Cat 108
- Wider field — 518mm vs 660mm focal length
- Faster optics at f/4.8 vs f/6
- Larger image circle (60mm) — supports bigger sensors
Best for — Astro-Physics 110mm f/6 StarFire GTX
- 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
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 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
Astro-Physics 110mm f/6 StarFire GTX — 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.
