telescopecomparison · 2-way
William Optics RedCat 91 WIFD vs Takahashi FSQ-85EDX
William Optics
RedCat 91 WIFD
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Takahashi
FSQ-85EDX
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+7% aperture
Faster by 0.4 f-stops
Specifications
| Specification | William Optics RedCat 91 WIFD | Takahashi FSQ-85EDX |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Petzval (5-element advanced) | Petzval APO |
| Aperture | 91mm | 85mm |
| Focal length | 448mm | 450mm |
| Native f/ratio | f/4.9 | f/5.3 |
| Image circle | 55mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 4.7kg | 4.0kg |
Advantages of William Optics RedCat 91 WIFD
- Faster optics at f/4.9 vs f/5.3
- Larger image circle (55mm) — supports bigger sensors
Advantages of Takahashi FSQ-85EDX
- Lighter (4kg vs 4.72kg) — easier to travel with
Best for — William Optics RedCat 91 WIFD
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Best for — Takahashi FSQ-85EDX
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics RedCat 91 WIFD — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.60° × 3.07°Scale: 1.73"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.01° × 2.01°Scale: 1.73"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.45° × 1.45°Scale: 1.73"/px
Takahashi FSQ-85EDX — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.58° × 3.06°Scale: 1.72"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.99° × 2.00°Scale: 1.72"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.44° × 1.44°Scale: 1.72"/px
William Optics RedCat 91 WIFD — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Takahashi FSQ-85EDX — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
