telescopecomparison · 2-way
William Optics Ultra-Cat 76 vs Askar FRA400
William Optics
Ultra-Cat 76
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
-9% focal length
+6% aperture
Faster by 0.8 f-stops
Specifications
| Specification | William Optics Ultra-Cat 76 | Askar FRA400 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Petzval (5-element advanced) | Petzval Quintuplet APO |
| Aperture | 76mm | 72mm |
| Focal length | 365mm | 400mm |
| Native f/ratio | f/4.8 | f/5.6 |
| Image circle | 50mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 3.8kg | 3.9kg |
Advantages of William Optics Ultra-Cat 76
- Faster optics at f/4.8 vs f/5.6
- Larger image circle (50mm) — supports bigger sensors
Advantages of Askar FRA400
Closely matched on the compared specs.
Best for — William Optics Ultra-Cat 76
- Large emission nebulae and star clusters
- Fast imaging — short exposures per sub
- Full-frame astro cameras and DSLRs
Best for — Askar FRA400
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics Ultra-Cat 76 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 5.65° × 3.77°Scale: 2.12"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.69° × 2.46°Scale: 2.12"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.77° × 1.77°Scale: 2.12"/px
Askar FRA400 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 5.16° × 3.44°Scale: 1.94"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.37° × 2.25°Scale: 1.94"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.62° × 1.62°Scale: 1.94"/px
William Optics Ultra-Cat 76 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Askar FRA400 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
