Not Designed for Immediate Observation at All Angles
The eyepiece is angled at 45 degrees, allowing for comfortable and casual stargazing—but not instant viewing from every position.
Recommended Stable Setup
For the BT81S-A optical tube, we recommend combining it with the HF2 fork mount and a ladder-type table with a free-stop mechanism, along with the highly rigid SXG-HAL130 tripod. This setup provides excellent stability for smooth and reliable observations.
Astronomical Binoculars BT81S-A
| Specification | Details |
|---|---|
| Objective Lens | 81 mm / Achromatic, single coating with MgF₂ |
| Focal Length / F-Ratio | 480 mm (f/5.9) |
| Resolving Power | 1.43 arcseconds |
| Limiting Magnitude | 11.3 |
| Light Gathering Power | 134× (compared to the unaided eye) |
| Dimensions (L × W × H) | 480 × 190 × 155 mm |
| Weight | 4100 g |
| Viewfinder | Arimiso-type base included (finder sold separately) |
Eyepiece Part
| Specification | Details |
|---|---|
| Eyepiece Size | 31.7 mm |
| Eyepiece (31.7 mm) | Sold separately |
| Photography Support | Not supported |
| Solar Observation | Not supported |
