telescopecomparison · 2-way
Borg 55FL vs Borg 90FL
Key differences
-50% focal length
-39% aperture
Faster by 1.1 f-stops
Specifications
| Specification | Borg 55FL | Borg 90FL |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Apo doublet fluorite | Apo doublet fluorite |
| Aperture | 55mm | 90mm |
| Focal length | 250mm | 500mm |
| Native f/ratio | f/4.5 | f/5.6 |
| Image circle | — | — |
| Full-frame support | No | No |
| Physical | ||
| Weight | 1.2kg | 2.5kg |
Advantages of Borg 55FL
- Wider field — 250mm vs 500mm focal length
- Faster optics at f/4.5 vs f/5.6
- Lighter (1.2kg vs 2.5kg) — easier to travel with
Advantages of Borg 90FL
- Tighter framing — 500mm vs 250mm focal length
- 64% more light-gathering aperture
Best for — Borg 55FL
- Wide-field nebulae and Milky Way regions
- Fast imaging — short exposures per sub
Best for — Borg 90FL
- Large emission nebulae and star clusters
Borg 55FL — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 8.25° × 5.50°Scale: 3.10"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 5.39° × 3.60°Scale: 3.10"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 2.59° × 2.59°Scale: 3.10"/px
Borg 90FL — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.13° × 2.75°Scale: 1.55"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.69° × 1.80°Scale: 1.55"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.29° × 1.29°Scale: 1.55"/px
Borg 55FL — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Borg 90FL — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.