telescopecomparison · 2-way
William Optics GT 81 vs SharpStar 76EDPH
William Optics
GT 81
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+14% focal length
+7% aperture
Slower by 0.4 f-stops
Specifications
| Specification | William Optics GT 81 | SharpStar 76EDPH |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo triplet FPL-53 | Doublet APO |
| Aperture | 81mm | 76mm |
| Focal length | 478mm | 418mm |
| Native f/ratio | f/5.9 | f/5.5 |
| Image circle | 44mm | 42mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 3.8kg | 3.2kg |
Advantages of William Optics GT 81
- Tighter framing — 478mm vs 418mm focal length
Advantages of SharpStar 76EDPH
- Wider field — 418mm vs 478mm focal length
- Faster optics at f/5.5 vs f/5.9
- Lighter (3.2kg vs 3.8kg) — easier to travel with
Best for — William Optics GT 81
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — SharpStar 76EDPH
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics GT 81 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.32° × 2.88°Scale: 1.62"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.82° × 1.88°Scale: 1.62"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.35° × 1.35°Scale: 1.62"/px
SharpStar 76EDPH — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.93° × 3.29°Scale: 1.86"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.22° × 2.15°Scale: 1.86"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.55° × 1.55°Scale: 1.86"/px
William Optics GT 81 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
SharpStar 76EDPH — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.