telescopecomparison · 2-way
ZWO FF90 APO vs Askar FRA500
ZWO
FF90 APO
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Key differences
+22% focal length
Slower by 1.2 f-stops
Specifications
| Specification | ZWO FF90 APO | Askar FRA500 |
|---|---|---|
| Optics | ||
| Type | refractor | Refractor |
| Optical design | Apo quadruplet ED | Petzval Quintuplet APO |
| Aperture | 90mm | 90mm |
| Focal length | 609mm | 500mm |
| Native f/ratio | f/6.8 | f/5.6 |
| Image circle | 44mm | 60mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 3.9kg | 5.4kg |
Advantages of ZWO FF90 APO
- Tighter framing — 609mm vs 500mm focal length
- Lighter (3.92kg vs 5.4kg) — easier to travel with
Advantages of Askar FRA500
- Wider field — 500mm vs 609mm focal length
- Faster optics at f/5.6 vs f/6.8
- Larger image circle (60mm) — supports bigger sensors
Best for — ZWO FF90 APO
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — Askar FRA500
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
ZWO FF90 APO — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 3.39° × 2.26°Scale: 1.27"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.21° × 1.48°Scale: 1.27"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.06° × 1.06°Scale: 1.27"/px
Askar FRA500 — 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
ZWO FF90 APO — recommended user
Best suited for intermediate imagers building a versatile kit running a portable travel rig.
Askar FRA500 — recommended user
Best suited for beginners and wide-field enthusiasts running a backyard imaging setup.
