telescopecomparison · 2-way
William Optics GT 71 vs William Optics GT 102
William Optics
GT 71
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics
GT 102
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
-40% focal length
-30% aperture
Faster by 1.0 f-stops
Specifications
| Specification | William Optics GT 71 | William Optics GT 102 |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Apo triplet FPL-53 | Apo triplet FPL-53 |
| Aperture | 71mm | 102mm |
| Focal length | 420mm | 703mm |
| Native f/ratio | f/5.9 | f/6.9 |
| Image circle | 44mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 3.4kg | 5.6kg |
Advantages of William Optics GT 71
- Wider field — 420mm vs 703mm focal length
- Faster optics at f/5.9 vs f/6.9
- Lighter (3.4kg vs 5.6kg) — easier to travel with
Advantages of William Optics GT 102
- Tighter framing — 703mm vs 420mm focal length
- 44% more light-gathering aperture
Best for — William Optics GT 71
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — William Optics GT 102
- Medium-sized galaxies and planetary nebulae
- Full-frame astro cameras and DSLRs
William Optics GT 71 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.91° × 3.27°Scale: 1.85"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.21° × 2.14°Scale: 1.85"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.54° × 1.54°Scale: 1.85"/px
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
William Optics GT 71 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics GT 102 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.