telescopecomparison · 2-way
Askar 107PHQ vs William Optics RedCat 91
Askar
107PHQ
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics
RedCat 91
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+51% focal length
+18% aperture
Slower by 1.5 f-stops
Specifications
| Specification | Askar 107PHQ | William Optics RedCat 91 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Petzval quintuplet FPL-51 | Petzval APO |
| Aperture | 107mm | 91mm |
| Focal length | 749mm | 496mm |
| Native f/ratio | f/7.0 | f/5.5 |
| Image circle | 44mm | 45mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 7.5kg | 4.3kg |
Advantages of Askar 107PHQ
- Tighter framing — 749mm vs 496mm focal length
- 18% more light-gathering aperture
Advantages of William Optics RedCat 91
- Wider field — 496mm vs 749mm focal length
- Faster optics at f/5.45 vs f/7
- Lighter (4.3kg vs 7.5kg) — easier to travel with
Best for — Askar 107PHQ
- Medium-sized galaxies and planetary nebulae
- Full-frame astro cameras and DSLRs
Best for — William Optics RedCat 91
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Askar 107PHQ — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 2.75° × 1.84°Scale: 1.04"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.80° × 1.20°Scale: 1.04"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.86° × 0.86°Scale: 1.04"/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
Askar 107PHQ — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics RedCat 91 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.