William Optics Gran Turismo GT71

William Optics Gran Turismo 71 II

The Gran Turismo 71 II is a compact 71 mm triplet apochromatic refractor with an Ohara FPL-53 objective. Its 419 mm focal length and f/5.9 focal ratio provide a wide field for deep-sky astrophotography and a portable optical tube for visual observing.

Optics and imaging

William Optics specifies a 44 mm image circle and support for full-frame, APS-C and Micro Four Thirds cameras. Optional Flat GT 1.0× and Flat6AIII 0.8× correctors provide separate imaging configurations; these are accessories rather than integral elements of the triplet objective.

Focusing and connections

The 2.5-inch dual-speed rack-and-pinion focuser has 93 mm travel and supports an electronic automatic focuser. An M63 to 2-inch visual back and 2-inch to 1.25-inch adapter provide the listed visual connections.

Camera spacing

With Flat GT, the manufacturer lists 56.6 mm backfocus using a 1.6 mm threaded spacer and removal of the front extender. With Flat6AIII, the listed backfocus is 64.1 mm with 9.1 mm adjustment. Use the spacing for the chosen corrector when assembling the camera train.

Portable mounting

The CNC-machined aluminium tube has a retractable dew shield, a 392–470 mm length range and a 2.95 kg optical-tube weight. Its dual-sided Vixen / Arca-Swiss plate offers two mounting profiles.

William Optics manufacturer documentation

Compatibility notes

Manufacturer-published named-model content completed. Optional correctors require their individually specified adapters and backfocus settings.

Additional specifications