telescopecomparison · 2-way
Tele Vue TV-85 vs William Optics RedCat 91
Tele Vue
TV-85
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
William Optics
RedCat 91
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+21% focal length
-7% aperture
Slower by 1.5 f-stops
Specifications
| Specification | Tele Vue TV-85 | William Optics RedCat 91 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo doublet | Petzval APO |
| Aperture | 85mm | 91mm |
| Focal length | 600mm | 496mm |
| Native f/ratio | f/7.0 | f/5.5 |
| Image circle | — | 45mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 2.9kg | 4.3kg |
Advantages of Tele Vue TV-85
- Tighter framing — 600mm vs 496mm focal length
- Lighter (2.9kg vs 4.3kg) — easier to travel with
Advantages of William Optics RedCat 91
- Wider field — 496mm vs 600mm focal length
- Faster optics at f/5.45 vs f/7
- Larger image circle (45mm) — supports bigger sensors
Best for — Tele Vue TV-85
- Large emission nebulae and star clusters
Best for — William Optics RedCat 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 RedCat 91 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.16° × 2.77°Scale: 1.56"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.71° × 1.81°Scale: 1.56"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.31° × 1.31°Scale: 1.56"/px
Tele Vue TV-85 — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
William Optics RedCat 91 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
