Fluorostar 91 APO Triplet Refractor - Space Grey
William Optics
From $1,998.00
2 stores
The William Optics Fluorostar 91 is a mid-sized apochromatic triplet refractor featuring a 91mm aperture with premium FPL-53 glass and STM coatings, delivering sharp, high-contrast images with a Strehl ratio exceeding 0.95. Equipped with a dual-speed 3.3" rack & pinion focuser, 360° field rotator, and William Optics' patented RotoLock 2" visual back system, it excels for both visual observation and astrophotography. Key features include an integrated saddle handle, built-in Bahtinov mask for precise focusing, and smooth, portable construction at just 4.2 kg, making it an ideal choice for astronomers and astrophotographers demanding professional optical performance in a compact package.
Specifications
| Weight (Tube Only) | 4.2 kg |
| Strehl Ratio | 0.95% |
| Weight (Fully Equipped) | 5.6 kg |
| Coatings | STM (Super Multi-Coatings) |
| Focal length | 540 mm |
| Visual Back | 2 inch RotoLock |
| Includes Soft Carry Case | ✓ |
| Optical design | Triplet APO |
| Aperture | 91 mm |
| Focal ratio | f/5.9 |
| Glass Type | FPL-53 |
| Focuser Type | 3.3 inch Dual-Speed Rack & Pinion |
| Includes Bahtinov Mask | ✓ |
| Field Rotator | 360 degrees |
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