FRA400 back focus
- Aperture
- 72 mm
- Focal length
- 400 mm at f/5.6
- Image circle
- 44 mm
- Rear thread
- M68
- Corrector
- Askar F3.9 0.7x Full Frame Reducer
Checked against the manufacturer’s documentation in September 2026.
Where to buy the Askar FRA400
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Cameras
| Camera | Back focus | Spacers | Result |
|---|---|---|---|
| Ares-C Pro | 55.0 mm | 21.0 mm | Exact |
| Artemis-C Pro | 55.0 mm | 37.5 mm | Exact |
| Neptune-C II | 55.0 mm | 26.0 mm | Exact |
| Poseidon-C Pro | 55.0 mm | 37.5 mm | Exact |
| Saturn-C SQR | 55.0 mm | 26.0 mm | Exact |
| Uranus-C | 55.0 mm | 26.0 mm | Exact |
| QHY183C | 55.0 mm | 21.0 mm | Exact |
| QHY183M | 55.0 mm | 21.0 mm | Exact |
| QHY268C (SBFL - Jan 2023 onward) | 55.0 mm | 19.5 mm | Exact |
| QHY268M (SBFL) | 55.0 mm | 19.5 mm | Exact |
| QHY294M Pro | 55.0 mm | 21.0 mm | Exact |
| QHY533C | 55.0 mm | 21.5 mm | Exact |
| QHY533M | 55.0 mm | 41.0 mm | Exact |
| QHY600M (SBFL) | 55.0 mm | 19.5 mm | Exact |
| ASI071MC Pro | 55.0 mm | 21.0 mm | Exact |
| ASI1600MM Pro | 55.0 mm | 32.0 mm | Exact |
| ASI183MC Pro | 55.0 mm | 32.0 mm | Exact |
| ASI183MM Pro | 55.0 mm | 32.0 mm | Exact |
| ASI2400MC Pro | 55.0 mm | 16.5 mm | Exact |
| ASI2600MC Duo | 55.0 mm | 16.5 mm | Exact |
| ASI2600MC Pro | 55.0 mm | 21.0 mm | Exact |
| ASI2600MM Duo | 55.0 mm | 16.5 mm | Exact |
| ASI2600MM Pro | 55.0 mm | 21.0 mm | Exact |
| ASI294MC Pro | 55.0 mm | 32.0 mm | Exact |
| ASI294MM Pro | 55.0 mm | 32.0 mm | Exact |
| ASI533MC Pro | 55.0 mm | 32.0 mm | Exact |
| ASI533MM Pro | 55.0 mm | 32.0 mm | Exact |
| ASI585MC Pro | 55.0 mm | 32.0 mm | Exact |
| ASI585MM Pro | 55.0 mm | 32.0 mm | Exact |
| ASI6200MC Pro | 55.0 mm | 16.5 mm | Exact |
| ASI6200MM Pro | 55.0 mm | 16.5 mm | Exact |