telescopecomparison · 2-way
William Optics Ultra-Cat 108 vs SharpStar 100QII
William Optics
Ultra-Cat 108
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
SharpStar
100QII
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
-6% focal length
+8% aperture
Faster by 0.7 f-stops
Specifications
| Specification | William Optics Ultra-Cat 108 | SharpStar 100QII |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Petzval (5-element advanced) | Quadruplet astrograph |
| Aperture | 108mm | 100mm |
| Focal length | 518mm | 550mm |
| Native f/ratio | f/4.8 | f/5.5 |
| Image circle | 60mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 8.0kg | 5.5kg |
Advantages of William Optics Ultra-Cat 108
- Faster optics at f/4.8 vs f/5.5
- Larger image circle (60mm) — supports bigger sensors
Advantages of SharpStar 100QII
- Lighter (5.5kg vs 7.96kg) — easier to travel with
Best for — William Optics Ultra-Cat 108
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Best for — SharpStar 100QII
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics Ultra-Cat 108 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.98° × 2.65°Scale: 1.50"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.60° × 1.74°Scale: 1.50"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.25° × 1.25°Scale: 1.50"/px
SharpStar 100QII — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.75° × 2.50°Scale: 1.41"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.45° × 1.64°Scale: 1.41"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.18° × 1.18°Scale: 1.41"/px
William Optics Ultra-Cat 108 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
SharpStar 100QII — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
