telescopecomparison · 2-way
William Optics Ultra-Cat 56 vs William Optics RedCat 51 WIFD
William Optics
Ultra-Cat 56
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics
RedCat 51 WIFD
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+8% focal length
+10% aperture
Specifications
| Specification | William Optics Ultra-Cat 56 | William Optics RedCat 51 WIFD |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Petzval (5-element advanced) | Petzval APO |
| Aperture | 56mm | 51mm |
| Focal length | 269mm | 250mm |
| Native f/ratio | f/4.8 | f/4.9 |
| Image circle | 50mm | 45mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 2.6kg | 1.6kg |
Advantages of William Optics Ultra-Cat 56
Closely matched on the compared specs.
Advantages of William Optics RedCat 51 WIFD
- Lighter (1.6kg vs 2.56kg) — easier to travel with
Best for — William Optics Ultra-Cat 56
- Wide-field nebulae and Milky Way regions
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Best for — William Optics RedCat 51 WIFD
- Wide-field nebulae and Milky Way regions
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
William Optics Ultra-Cat 56 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 7.67° × 5.11°Scale: 2.88"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 5.01° × 3.34°Scale: 2.88"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 2.41° × 2.41°Scale: 2.88"/px
William Optics RedCat 51 WIFD — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 8.25° × 5.50°Scale: 3.10"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 5.39° × 3.60°Scale: 3.10"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 2.59° × 2.59°Scale: 3.10"/px
William Optics Ultra-Cat 56 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics RedCat 51 WIFD — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
