telescopecomparison · 2-way
Orion 8" f/3.9 Newtonian Astrograph vs Astro-Physics 155mm f/6 StarFire CS
Orion
8" f/3.9 Newtonian Astrograph
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Astro-Physics
155mm f/6 StarFire CS
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Key differences
-14% focal length
+31% aperture
Faster by 2.1 f-stops
Specifications
| Specification | Orion 8" f/3.9 Newtonian Astrograph | Astro-Physics 155mm f/6 StarFire CS |
|---|---|---|
| Optics | ||
| Type | newtonian | refractor |
| Optical design | Newtonian astrograph | Christen Superachromat (4-element) |
| Aperture | 203mm | 155mm |
| Focal length | 800mm | 930mm |
| Native f/ratio | f/3.9 | f/6.0 |
| Image circle | — | 64mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 10.5kg | 10.9kg |
Advantages of Orion 8" f/3.9 Newtonian Astrograph
- Wider field — 800mm vs 930mm focal length
- 31% more light-gathering aperture
- Faster optics at f/3.9 vs f/6
Advantages of Astro-Physics 155mm f/6 StarFire CS
- Tighter framing — 930mm vs 800mm focal length
- Larger image circle (64mm) — supports bigger sensors
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 — Astro-Physics 155mm f/6 StarFire CS
- 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
Astro-Physics 155mm f/6 StarFire CS — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 2.22° × 1.48°Scale: 0.83"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 1.45° × 0.97°Scale: 0.83"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 0.70° × 0.70°Scale: 0.83"/px
Orion 8" f/3.9 Newtonian Astrograph — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
Astro-Physics 155mm f/6 StarFire CS — recommended user
Best suited for intermediate imagers building a versatile kit running a backyard imaging setup.
