Fluorostar 91
A precision-engineered apochromatic triplet refractor designed for discerning astronomers and astrophotographers. This mid-sized telescope features a 91mm aperture with FPL-53 glass, delivering sharp, high-contrast images and an impressive Strehl ratio exceeding 0.95.
Equipped with user-centric features, the FLT91 includes an integrated saddle handle, a 360º field rotator, a dual-speed 3.3" Rack & Pinion focuser, and a 2" Rotolock system. These enhance usability and provide stability for both visual and photographic applications.
Astrophotographers will find the built-in Bahtinov mask invaluable for achieving perfect focus effortlessly. Compatible with the Flat 6AIII, Flat 68III, and Ultra Flat 91, the FLT91 allows precise back-focus adjustments.
Constructed with William Optics' signature quality, the FLT91 is both lightweight and durable, weighing 4.2 kg and 5.6 kg fully equipped. It comes with a soft carry case for easy transportation and protection.
Ideal for capturing celestial phenomena, the William Optics FLT91 is a top choice for those seeking advanced optical performance in a portable package.
Pairs well with
- Lens Type
- Triplet Apochromatic Prime Lens
- Focal Length
- 540 mm
- Diameter
- 91 mm
- Focal Ratio
- f/5.9
- Image circle
- 43 mm
- Focuser
- 3.3" R&P Focuser
- Compatible with EAF
- Adapter Included
- M92 Rotator
- M92 Extender
- M92 → 2" RotoLock
- Optional Flattener
- FLAT68III 1.0x (requires adapter)
- FLAT6AIII 0.8x (requires adapter)
- Ultra Flat 0.79x
- Camera Format
- Full Frame
- APS-C
- M4/3
- Tube Length
- 441 mm - 510 mm
- OTA Weight
- 4.16 kg / 9.17 lbs
- Total Weight
- 5.57 kg / 12.28 lbs
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