telescopecomparison · 2-way
William Optics FLT 91 vs SharpStar 100QII
William Optics
FLT 91
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
SharpStar
100QII
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
-9% aperture
Slower by 0.4 f-stops
Specifications
| Specification | William Optics FLT 91 | SharpStar 100QII |
|---|---|---|
| Optics | ||
| Type | Refractor | refractor |
| Optical design | Triplet APO | Quadruplet astrograph |
| Aperture | 91mm | 100mm |
| Focal length | 540mm | 550mm |
| Native f/ratio | f/5.9 | f/5.5 |
| Image circle | 44mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 4.5kg | 5.5kg |
Advantages of William Optics FLT 91
- Lighter (4.5kg vs 5.5kg) — easier to travel with
Advantages of SharpStar 100QII
- Faster optics at f/5.5 vs f/5.9
Best for — William Optics FLT 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — SharpStar 100QII
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics FLT 91 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.82° × 2.55°Scale: 1.44"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.49° × 1.67°Scale: 1.44"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.20° × 1.20°Scale: 1.44"/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 FLT 91 — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
SharpStar 100QII — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.