telescopecomparison · 2-way
Tele Vue TV-85 vs William Optics FLT 91
Tele Vue
TV-85
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
William Optics
FLT 91
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Key differences
+11% focal length
-7% aperture
Slower by 1.1 f-stops
Specifications
| Specification | Tele Vue TV-85 | William Optics FLT 91 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo doublet | Triplet APO |
| Aperture | 85mm | 91mm |
| Focal length | 600mm | 540mm |
| Native f/ratio | f/7.0 | f/5.9 |
| Image circle | — | 44mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 2.9kg | 4.5kg |
Advantages of Tele Vue TV-85
- Tighter framing — 600mm vs 540mm focal length
- Lighter (2.9kg vs 4.5kg) — easier to travel with
Advantages of William Optics FLT 91
- Faster optics at f/5.9 vs f/7
- Larger image circle (44mm) — supports bigger sensors
Best for — Tele Vue TV-85
- Large emission nebulae and star clusters
Best for — William Optics FLT 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Tele Vue TV-85 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.44° × 2.29°Scale: 1.29"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.24° × 1.50°Scale: 1.29"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.08° × 1.08°Scale: 1.29"/px
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 TV-85 — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
William Optics FLT 91 — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.