William Optics Fluorostar 91 APO
AED 10,080.00
- 91mm FPL-53 Apochromatic Triplet Lens with 0.95+ Strehl Ratio
- 540mm, f/5.9 Focal Length
- Dual-speed rack and pinion focuser with “Rotolock” clamping
- Field rotator with degree markings and position lock
- OTA Weight 4.2kg / 5.6kg with Rings / Dovetail / Accessories
- Supplied with a Soft Carry Case
- William Optics´ patented Bahtinov mask
Available on backorder
Description
William Optics Fluorostar 91 APO is a three element air-spaced apochromatic refractor with a focal ratio of f/5.9 and a focal length of 540mm. Utilizing FPL-53 synthetic fluorite glass with STM coatings, this telescope provides excellent aberration correction and amazing optical performance.
The 3.3″ dual speed rack & pinion focuser is smooth, stable and reliable, providing no slippage over long imaging sessions. The super smooth field rotator includes markings for every degree, and a solid thumbscrew position lock.
The CNC-machined and anodized handle bar with finder-style saddle is perfect for attaching a guide scope or other accessories. The FLT 91 also includes William Optics’ innovative clear Bahtinov mask integrated into the lens cap. The Rotolock 2 inch adapter provides for a solid and efficient connection for a William Optics 2 inch diagonal, and other accessories.
William Optics uses high quality steel lens cells for their Gran Turismo and FLT triplet refractors. This is perfect for temperature compensation and will prevent pinched optics in cold weather conditions.
For best imaging results, it is recommended to pair the FLT 91 with its matching Flat6AIII 0.8x field flattener/reducer (with M92 adapter ring) or Flat68AIII 1.0x flattener.
BAHTINOV MASK
The retractable dew shield features a removable lens cover, with our patented Bahtinov Mask revealed by unscrewing the face plate. The transparent design allows for brighter star patterns and precise focusing for astrophotography.
William Optics Fluorostar 91 APO Specifications
| Lens Type | Apochromatic Triplet Prime Lens |
| Focal Length | 540mm |
| Diameter | 91mm |
| Focal Ratio | f/5.9 |
| Focuser | Dual Speed 3.3″ R&P Focuser |
| Colour | Red | Gold | Space grey |
| Lens Material | FPL-53 |
| Strehl Ratio | 0.95+ |
| Camera Format | Full Frame DSLR / Mirrorless / CMOS / CCD |
| Test Report | Zygo test report available at additional cost |
| T-Mounts Supported | Canon EF, RF Nikon F, Z Sony E Pentax K Micro Four Thirds (M4/3) FUJI X |
| Retracted Length | 441mm without rings (485mm with rings fitted) |
| Extended Length | 510mm |
| Extension Tube Length | 40mm |
| OTA Weight | 4.165Kg |
| Total Weight | 5.575Kg |
| Extension Tube Weight | 0.105Kg |
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