Fluorostar 91 / FLT91 APO
William Optics
From $1,998.00
4 stores
The William Optics FLT91 is an ideal apochromatic refractor for both visual and photographic astronomers, featuring a 91mm aperture with FPL-53 glass and STM-coatings that deliver excellent optical performance. This mid-sized telescope delivers sharp, high-contrast images with an impressive Strehl ratio exceeding 0.95. Equipped with a Rotolock 2-inch adapter for efficient accessory connection and a retractable dew shield with patented Bahtinov Mask for precise astrophotographic focusing, the FLT91 is lightweight and portable at 4.2 kg (OTA only) and 5.6 kg fully equipped.
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Fluorostar 91 APO Triplet Refractor - Red
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Specifications
| Coating | STM |
| Optical design | Triplet Refractor |
| Focal length | 540 mm |
| Focal ratio | f/5.9 |
| Highest magnification | 182 |
| Optics type | Refractor |
| Aperture | 91 mm |
| OTA Weight | 4.165 lb |
| Focuser Type | 3.3-inch Rack and Pinion |
| Telescope Length (Retracted) | 45 cm |
| Weight (Fully Equipped) | 5.6 kg |
| Image Circle | 45 mm |
| Glass Type | FPL-53 |
| Field Rotator | 360 degrees with degree markings |
| Strehl Ratio | 0.95% |
| Back Focus Available | 40 mm |
| Visual Back | Rotolock 2-inch adapter |