telescopecomparison · 2-way
Sky-Watcher Evolux 82ED vs William Optics RedCat 91
Sky-Watcher
Evolux 82ED
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics
RedCat 91
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
-10% aperture
Slower by 0.6 f-stops
Specifications
| Specification | Sky-Watcher Evolux 82ED | William Optics RedCat 91 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo doublet FPL-53 | Petzval APO |
| Aperture | 82mm | 91mm |
| Focal length | 499mm | 496mm |
| Native f/ratio | f/6.1 | f/5.5 |
| Image circle | 44mm | 45mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 3.6kg | 4.3kg |
Advantages of Sky-Watcher Evolux 82ED
- Lighter (3.6kg vs 4.3kg) — easier to travel with
Advantages of William Optics RedCat 91
- 11% more light-gathering aperture
- Faster optics at f/5.45 vs f/6.1
Best for — Sky-Watcher Evolux 82ED
- Large emission nebulae and star clusters
Best for — William Optics RedCat 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Sky-Watcher Evolux 82ED — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.13° × 2.76°Scale: 1.55"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.70° × 1.80°Scale: 1.55"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.30° × 1.30°Scale: 1.55"/px
William Optics RedCat 91 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.16° × 2.77°Scale: 1.56"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.71° × 1.81°Scale: 1.56"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.31° × 1.31°Scale: 1.56"/px
Sky-Watcher Evolux 82ED — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics RedCat 91 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.