telescopecomparison · 2-way
William Optics Zenithstar 73 II vs Askar FRA400
William Optics
Zenithstar 73 II
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+8% focal length
Slower by 0.3 f-stops
Specifications
| Specification | William Optics Zenithstar 73 II | Askar FRA400 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo doublet FPL-53 | Petzval Quintuplet APO |
| Aperture | 73mm | 72mm |
| Focal length | 430mm | 400mm |
| Native f/ratio | f/5.9 | f/5.6 |
| Image circle | 44mm | 44mm |
| Full-frame support | No | Yes |
| Physical | ||
| Weight | 2.4kg | 3.9kg |
Advantages of William Optics Zenithstar 73 II
- Lighter (2.4kg vs 3.9kg) — easier to travel with
Advantages of Askar FRA400
- Faster optics at f/5.6 vs f/5.9
Best for — William Optics Zenithstar 73 II
- Large emission nebulae and star clusters
Best for — Askar FRA400
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
William Optics Zenithstar 73 II — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.80° × 3.20°Scale: 1.80"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.13° × 2.09°Scale: 1.80"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.51° × 1.51°Scale: 1.80"/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 Zenithstar 73 II — 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.