telescopecomparison · 2-way
William Optics GT 102 vs Takahashi FSQ-85EDX
William Optics
GT 102
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Takahashi
FSQ-85EDX
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+56% focal length
+20% aperture
Slower by 1.6 f-stops
Specifications
| Specification | William Optics GT 102 | Takahashi FSQ-85EDX |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo triplet FPL-53 | Petzval APO |
| Aperture | 102mm | 85mm |
| Focal length | 703mm | 450mm |
| Native f/ratio | f/6.9 | f/5.3 |
| Image circle | 44mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 5.6kg | 4.0kg |
Advantages of William Optics GT 102
- Tighter framing — 703mm vs 450mm focal length
- 20% more light-gathering aperture
Advantages of Takahashi FSQ-85EDX
- Wider field — 450mm vs 703mm focal length
- Faster optics at f/5.3 vs f/6.9
- Lighter (4kg vs 5.6kg) — easier to travel with
Best for — William Optics GT 102
- Medium-sized galaxies and planetary nebulae
- Full-frame astro cameras and DSLRs
Best for — Takahashi FSQ-85EDX
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics GT 102 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 2.93° × 1.96°Scale: 1.10"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.92° × 1.28°Scale: 1.10"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.92° × 0.92°Scale: 1.10"/px
Takahashi FSQ-85EDX — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.58° × 3.06°Scale: 1.72"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.99° × 2.00°Scale: 1.72"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.44° × 1.44°Scale: 1.72"/px
William Optics GT 102 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Takahashi FSQ-85EDX — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.