telescopecomparison · 2-way
William Optics RedCat 91 vs Sky-Watcher Evolux 82ED
William Optics
RedCat 91
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Sky-Watcher
Evolux 82ED
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+11% aperture
Faster by 0.6 f-stops
Specifications
| Specification | William Optics RedCat 91 | Sky-Watcher Evolux 82ED |
|---|---|---|
| Optics | ||
| Type | Refractor | refractor |
| Optical design | Petzval APO | Apo doublet FPL-53 |
| Aperture | 91mm | 82mm |
| Focal length | 496mm | 499mm |
| Native f/ratio | f/5.5 | f/6.1 |
| Image circle | 45mm | 44mm |
| Full-frame support | Yes | No |
| Physical | ||
| Weight | 4.3kg | 3.6kg |
Advantages of William Optics RedCat 91
- 11% more light-gathering aperture
- Faster optics at f/5.45 vs f/6.1
Advantages of Sky-Watcher Evolux 82ED
- Lighter (3.6kg vs 4.3kg) — easier to travel with
Best for — William Optics RedCat 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — Sky-Watcher Evolux 82ED
- Large emission nebulae and star clusters
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 — 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 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Sky-Watcher Evolux 82ED — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.