William Optics Apochromatic refractor AP 81/478 Gran Turismo 81 IV OTA Guidescope-Set (69218)

William Optics Apochromatic Refractor AP 81/478 Gran Turismo 81 IV OTA Guidescope Set (69218)

This set includes the William Optics AP 81/478 Gran Turismo 81 IV optical tube assembly and the William Optics UniGuide 50 mm guidescope in red.

The Gran Turismo 81 IV is an apochromatic triplet refractor featuring an FPL-53 element for outstanding color correction and high contrast performance. It is a versatile instrument designed for both visual observation and astrophotography.

For visual use, the telescope can be combined with an optional zenith mirror to provide high-contrast views of the Moon and planets. Thanks to its sharp star rendering and fast optics, it is also well suited for observing deep-sky objects such as star clusters, galaxies, and nebulae. Globular clusters in particular benefit from the crisp and detailed image quality.

For astrophotography, the optional Flat6AIII flattener and reducer is recommended. The optical system delivers a flat field with stable focus suitable for full-frame cameras. Integrated prism rail adapters in the handle allow the attachment of a guiding scope, which can function either as a finder scope or as a guiding solution.

The telescope is equipped with a robust 2.5-inch rack-and-pinion focuser featuring a long focusing travel, 1:10 fine focusing reduction, and a temperature display. A 1.25-inch eyepiece adapter is included.

The Gran Turismo apochromat is built for durability and portability, making it ideal for travel and mobile astronomy. It performs reliably under dark skies and is well suited for exploring objects from the Messier and NGC catalogues. Its stable construction and user-friendly design make it a dependable companion from the first observing session onward.

A special feature of the latest William Optics apochromats is the precisely calculated Bahtinov focus mask made from optical acrylic glass. With 92 percent transparency, it produces a diffraction pattern approximately three times brighter than traditional metal masks. This allows clearer focusing, even when using fainter stars.

Optical Specifications

• Optical design: Refractor, apochromat

• Lens design: Triplet with FPL-53 element

• Aperture: 81 mm

• Focal length: 478 mm

• Focal ratio: f/5.9

• Resolving power: 1.70 arcseconds

• Limiting magnitude: 11.3

• Light gathering power: 130x

• Maximum useful magnification: 162x

• SMC multi-coating

• Internal stray light baffles

Tube and Construction

• Tube weight: 3.9 kg

• Tube length: 460 mm

• Carrying length: 390 mm

• Series: Gran Turismo

• Color: Red

Focuser and Mechanics

• 2.5-inch rack-and-pinion focuser

• 1:10 fine focusing reduction

• Free aperture: 64 mm

• Eyepiece connection: 2 inch

• Eyepiece adapter: 2 inch and 1.25 inch

• Telescope-side connection thread: M63

• Not motorized

• Ring clamps included

Included Accessories

• UniGuide 50 mm guidescope

• Bahtinov focusing mask

• Dew shield

• Vixen-style prism rail

• Carrying handle

• Carry case

• Optical tube assembly only (no mount included)

Application

• Astrophotography: Very good suitability

• Nebulae and galaxies: Yes

• Moon and planets: Yes

• Nature observation: No

• Solar observation: Only with an appropriate solar filter

• Recommended for advanced users

• Not specifically intended for permanent observatory use