telescopecomparison · 2-way
William Optics FLT 156 vs Radian Raptor 75
William Optics
FLT 156
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+168% focal length
+108% aperture
Slower by 1.6 f-stops
Specifications
| Specification | William Optics FLT 156 | Radian Raptor 75 |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Apo triplet FPL-53 | Petzval quintuplet |
| Aperture | 156mm | 75mm |
| Focal length | 1085mm | 405mm |
| Native f/ratio | f/7.0 | f/5.4 |
| Image circle | 52mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 11.5kg | 4.5kg |
Advantages of William Optics FLT 156
- Tighter framing — 1085mm vs 405mm focal length
- 108% more light-gathering aperture
- Larger image circle (52mm) — supports bigger sensors
Advantages of Radian Raptor 75
- Wider field — 405mm vs 1085mm focal length
- Faster optics at f/5.4 vs f/7
- Lighter (4.5kg vs 11.5kg) — easier to travel with
Best for — William Optics FLT 156
- Medium-sized galaxies and planetary nebulae
- Full-frame astro cameras and DSLRs
Best for — Radian Raptor 75
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics FLT 156 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 1.90° × 1.27°Scale: 0.71"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.24° × 0.83°Scale: 0.71"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.60° × 0.60°Scale: 0.71"/px
Radian Raptor 75 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 5.09° × 3.40°Scale: 1.91"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.32° × 2.22°Scale: 1.91"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.60° × 1.60°Scale: 1.91"/px
William Optics FLT 156 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Radian Raptor 75 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.