telescopecomparison · 2-way
Askar 71F vs William Optics GT 71
William Optics
GT 71
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
Key differences
+17% focal length
Slower by 1.0 f-stops
Specifications
| Specification | Askar 71F | William Optics GT 71 |
|---|---|---|
| Optics | ||
| Type | refractor | refractor |
| Optical design | Petzval quintuplet FPL-51 | Apo triplet FPL-53 |
| Aperture | 71mm | 71mm |
| Focal length | 490mm | 420mm |
| Native f/ratio | f/6.9 | f/5.9 |
| Image circle | 44mm | 44mm |
| Full-frame support | Yes | Yes |
| Physical | ||
| Weight | 3.2kg | 3.4kg |
Advantages of Askar 71F
- Tighter framing — 490mm vs 420mm focal length
Advantages of William Optics GT 71
- Wider field — 420mm vs 490mm focal length
- Faster optics at f/5.9 vs f/6.9
Best for — Askar 71F
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Best for — William Optics GT 71
- Large emission nebulae and star clusters
- Full-frame astro cameras and DSLRs
Askar 71F — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.21° × 2.81°Scale: 1.58"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 2.75° × 1.84°Scale: 1.58"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.32° × 1.32°Scale: 1.58"/px
William Optics GT 71 — typical FOV & scale
- With Full-frame (36×24mm, 3.76µm)FOV: 4.91° × 3.27°Scale: 1.85"/px
- With APS-C (23.5×15.7mm, 3.76µm)FOV: 3.21° × 2.14°Scale: 1.85"/px
- With IMX533 square (11.3×11.3mm, 3.76µm)FOV: 1.54° × 1.54°Scale: 1.85"/px
Askar 71F — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.
William Optics GT 71 — recommended user
Best suited for beginners and wide-field enthusiasts running a portable travel rig.