telescopecomparison · 2-way
SharpStar 61EDPH III vs William Optics Ultra-Cat 56
SharpStar
61EDPH III
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics
Ultra-Cat 56
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+25% focal length
+9% aperture
Slower by 0.7 f-stops
Specifications
| Specification | SharpStar 61EDPH III | William Optics Ultra-Cat 56 |
|---|---|---|
| Optics | ||
| Type | Refractor | refractor |
| Optical design | Doublet APO | Petzval (5-element advanced) |
| Aperture | 61mm | 56mm |
| Focal length | 335mm | 269mm |
| Native f/ratio | f/5.5 | f/4.8 |
| Image circle | 32mm | 50mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 2.4kg | 2.6kg |
Advantages of SharpStar 61EDPH III
- Tighter framing — 335mm vs 269mm focal length
Advantages of William Optics Ultra-Cat 56
- Wider field — 269mm vs 335mm focal length
- Faster optics at f/4.8 vs f/5.5
- Larger image circle (50mm) — supports bigger sensors
Best for — SharpStar 61EDPH III
- Wide-field nebulae and Milky Way regions
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
SharpStar 61EDPH III — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 6.16° × 4.11°Scale: 2.32"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 4.02° × 2.69°Scale: 2.32"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.93° × 1.93°Scale: 2.32"/px
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
SharpStar 61EDPH III — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics Ultra-Cat 56 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
