William Optics Gran Turismo GT81 WIFD OTA — 81 mm triplet apochromat This refractor provides a 478 mm focal length at f/5.9. The manufacturer lists a 45 mm image circle and optional correctors for photographic use.
Manufacturer model: William Optics Gran Turismo GT81 WIFD OTA · Specifications checked against manufacturer data on 2026-11-03
This refractor provides a 478 mm focal length at f/5.9. The manufacturer lists a 45 mm image circle and optional correctors for photographic use.
The WIFD rack and pinion focuser provides 75 mm travel. Connections comprise M92 rotator; M92 to M63 adapter.
Manufacturer-listed options: Flat6AIII 0.8x, Flat68III 1.0x, Flat GT 1.0x. Each combination has a specific spacing and adapter arrangement; see the individual settings in the specifications. A corrector is an optional accessory.
Tube length is 420–500 mm and OTA weight is 3.58 kg. Total weight is 4.56 kg.
William Optics manufacturer manual
The objective uses Ohara FPL-53 ED glass for colour correction. The manufacturer lists a dual-sided Vixen / Arca-Swiss dovetail for mounting. For photographic use, select the correct flattener or reducer and its specified adapters; telescope focal length and corrector spacing are separate specifications.
Prime-lens telescope: corrector compatibility and spacing are model-specific. Optional correctors are listed, not assumed included; corrector adapters may be required.
| Flat gt with front adapter spacing | 55 mm; requires 4-inch OTA extender, removal of 1.6 mm spacer and 30.85 mm flattener front extender |
|---|---|
| Flat6aiii spacing | 62.1 mm backfocus; 7.1 mm adjustment |
| Flat68iii with back extender spacing | 57 mm backfocus; 2 mm adjustment |
Data sheet
William Optics Gran Turismo GT81 WIFD OTA — 81 mm triplet apochromat This refractor provides a 478 mm focal length at f/5.9. The manufacturer lists a 45 mm image circle and optional correctors for photographic use.
Manufacturer model: William Optics Gran Turismo GT81 WIFD OTA · Specifications checked against manufacturer data on 2026-11-03
