telescopecomparison · 2-way
Orion 8" f/3.9 Newtonian Astrograph vs William Optics FLT 120
Orion
8" f/3.9 Newtonian Astrograph
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics
FLT 120
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
+69% aperture
Faster by 2.6 f-stops
Specifications
| Specification | Orion 8" f/3.9 Newtonian Astrograph | William Optics FLT 120 |
|---|---|---|
| Optics | ||
| Type | newtonian | Refractor |
| Optical design | Newtonian astrograph | Triplet APO |
| Aperture | 203mm | 120mm |
| Focal length | 800mm | 780mm |
| Native f/ratio | f/3.9 | f/6.5 |
| Image circle | — | 44mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 10.5kg | 7.7kg |
Advantages of Orion 8" f/3.9 Newtonian Astrograph
- 69% more light-gathering aperture
- Faster optics at f/3.9 vs f/6.5
Advantages of William Optics FLT 120
- Larger image circle (44mm) — supports bigger sensors
- Lighter (7.7kg vs 10.5kg) — easier to travel with
Best for — Orion 8" f/3.9 Newtonian Astrograph
- Medium-sized galaxies and planetary nebulae
- Fast imaging — short exposures per sub
- Faint-object imaging under dark skies
Best for — William Optics FLT 120
- Medium-sized galaxies and planetary nebulae
- Full-frame astro cameras and DSLRs
Orion 8" f/3.9 Newtonian Astrograph — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 2.58° × 1.72°Scale: 0.97"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.68° × 1.12°Scale: 0.97"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.81° × 0.81°Scale: 0.97"/px
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
Orion 8" f/3.9 Newtonian Astrograph — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
William Optics FLT 120 — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
