telescope
Borg
90FL
90mm Apo doublet fluorite · 500mm f/5.6
Modular fluorite.
Best for
- Large emission nebulae and star clusters
Specifications
| Optics | |
| Type | refractor |
| Optical design | Apo doublet fluorite |
| Aperture | 90mm |
| Focal length | 500mm |
| Native f/ratio | f/5.6 |
| Image circle | — |
| Full-frame support | No |
| Physical | |
| Weight | 2.5kg |
Typical FOV & image 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
Typical targets
- M48 — Open Cluster M48Open Cluster · 54′Plan this target
- IC 434 — Horsehead NebulaEmission Nebula · 60′Plan this target
- NGC 869/884 — Double ClusterOpen Cluster · 60′Plan this target
- NGC 2264 — Christmas Tree ClusterEmission Nebula · 60′Plan this target
- NGC 6992 — Eastern VeilSupernova Remnant · 60′Plan this target
- NGC 7822 — Cepheus HII RegionEmission Nebula · 60′Plan this target
