telescopecomparison · 2-way
William Optics FLT 91 vs Tele Vue NP101is
William Optics
FLT 91
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Tele Vue
NP101is
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Key differences
-10% aperture
Slower by 0.5 f-stops
Specifications
| Specification | William Optics FLT 91 | Tele Vue NP101is |
|---|---|---|
| Optics | ||
| Type | Refractor | Refractor |
| Optical design | Triplet APO | Petzval |
| Aperture | 91mm | 101mm |
| Focal length | 540mm | 540mm |
| Native f/ratio | f/5.9 | f/5.4 |
| Image circle | 44mm | 40mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 4.5kg | 4.5kg |
Advantages of William Optics FLT 91
Closely matched on the compared specs.
Advantages of Tele Vue NP101is
- 11% more light-gathering aperture
- Faster optics at f/5.4 vs f/5.9
Best for — William Optics FLT 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — Tele Vue NP101is
- 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
Tele Vue NP101is — 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
William Optics FLT 91 — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Tele Vue NP101is — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.