telescopecomparison · 2-way
William Optics GT 102 vs William Optics RedCat 71
William Optics
GT 102
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics
RedCat 71
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+101% focal length
+44% aperture
Slower by 2.0 f-stops
Specifications
| Specification | William Optics GT 102 | William Optics RedCat 71 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo triplet FPL-53 | Petzval APO |
| Aperture | 102mm | 71mm |
| Focal length | 703mm | 350mm |
| Native f/ratio | f/6.9 | f/4.9 |
| Image circle | 44mm | 45mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 5.6kg | 2.7kg |
Advantages of William Optics GT 102
- Tighter framing — 703mm vs 350mm focal length
- 44% more light-gathering aperture
Advantages of William Optics RedCat 71
- Wider field — 350mm vs 703mm focal length
- Faster optics at f/4.9 vs f/6.9
- Lighter (2.7kg 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 — William Optics RedCat 71
- Wide-field nebulae and Milky Way regions
- Fast imaging — short exposures per sub
- 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
William Optics RedCat 71 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 5.89° × 3.93°Scale: 2.22"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.85° × 2.57°Scale: 2.22"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.85° × 1.85°Scale: 2.22"/px
William Optics GT 102 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics RedCat 71 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.