telescopecomparison · 2-way
William Optics FLT 120 vs Askar FRA400
William Optics
FLT 120
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+95% focal length
+67% aperture
Slower by 0.9 f-stops
Specifications
| Specification | William Optics FLT 120 | Askar FRA400 |
|---|---|---|
| Optics | ||
| Type | Refractor | Refractor |
| Optical design | Triplet APO | Petzval Quintuplet APO |
| Aperture | 120mm | 72mm |
| Focal length | 780mm | 400mm |
| Native f/ratio | f/6.5 | f/5.6 |
| Image circle | 44mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 7.7kg | 3.9kg |
Advantages of William Optics FLT 120
- Tighter framing — 780mm vs 400mm focal length
- 67% more light-gathering aperture
Advantages of Askar FRA400
- Wider field — 400mm vs 780mm focal length
- Faster optics at f/5.6 vs f/6.5
- Lighter (3.9kg vs 7.7kg) — easier to travel with
Best for — William Optics FLT 120
- 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 120 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 2.64° × 1.76°Scale: 0.99"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.73° × 1.15°Scale: 0.99"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.83° × 0.83°Scale: 0.99"/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 120 — 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.