telescope
William Optics
Ultra-Cat 108
108mm Petzval (5-element advanced) · 518mm f/4.8
Large-aperture Petzval astrograph; medium format capable.
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Product specifications can change. Please verify specifications and compatibility with the manufacturer or retailer before purchasing.
Best for
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Specifications
| Optics | |
| Type | refractor |
| Optical design | Petzval (5-element advanced) |
| Aperture | 108mm |
| Focal length | 518mm |
| Native f/ratio | f/4.8 |
| Image circle | 60mm |
| Full-frame support | Yes |
| Physical | |
| Weight | 8.0kg |
Typical FOV & image scale
With Full-frame (36×24mm, 3.76µm)
FOV 3.98° × 2.65°
Scale 1.50″/px
With APS-C (23.5×15.7mm, 3.76µm)
FOV 2.60° × 1.74°
Scale 1.50″/px
With IMX533 square (11.3×11.3mm, 3.76µm)
FOV 1.25° × 1.25°
Scale 1.50″/px
Typical targets
- M48 — Open Cluster M48Open Cluster · 54′Plan this target
- NGC 6357 — Lobster NebulaEmission Nebula · 50′Plan this target
- IC 443 — Jellyfish NebulaSupernova Remnant · 50′Plan this target
- Sh2-155 — Cave NebulaEmission Nebula · 50′Plan this target
- IC 434 — Horsehead NebulaEmission Nebula · 60′Plan this target
- NGC 869/884 — Double ClusterOpen Cluster · 60′Plan this target
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Source: williamoptics.com




