telescopecomparison · 2-way
William Optics FLT 156 vs Askar FRA400
William Optics
FLT 156
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+171% focal length
+117% aperture
Slower by 1.4 f-stops
Specifications
| Specification | William Optics FLT 156 | Askar FRA400 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo triplet FPL-53 | Petzval Quintuplet APO |
| Aperture | 156mm | 72mm |
| Focal length | 1085mm | 400mm |
| Native f/ratio | f/7.0 | f/5.6 |
| Image circle | 52mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 11.5kg | 3.9kg |
Advantages of William Optics FLT 156
- Tighter framing — 1085mm vs 400mm focal length
- 117% more light-gathering aperture
- Larger image circle (52mm) — supports bigger sensors
Advantages of Askar FRA400
- Wider field — 400mm vs 1085mm focal length
- Faster optics at f/5.6 vs f/7
- Lighter (3.9kg 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 — Askar FRA400
- 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
Askar FRA400 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 5.16° × 3.44°Scale: 1.94"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.37° × 2.25°Scale: 1.94"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.62° × 1.62°Scale: 1.94"/px
William Optics FLT 156 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Askar FRA400 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.