William Optics Apochromatic refractor Pleiades 181 AP 181/998 Astrograph OTA (84720)

William Optics Apochromatic Refractor Pleiades 181 AP 181/998 Astrograph OTA (84720)

The Pleiades 181 is a high-performance astrograph developed almost exclusively for serious astrophotography. Featuring premium OHARA FPL-53 glass and an integrated field corrector, this telescope delivers outstanding image sharpness and color accuracy across a fully corrected 55 mm image circle. With its fast f/5.5 focal ratio, it enables shorter exposure times while fully illuminating full-frame sensors. The elegant white and red design is inspired by the Pleiades star cluster, combining visual appeal with professional functionality.

This advanced quadruplet apochromat incorporates a sophisticated 7-element optical system to produce crisp, high-contrast images with minimal aberrations. The powerful 181 mm aperture ensures impressive light-gathering capability, making it ideal for deep-sky objects such as nebulae and galaxies.

A large 3.7-inch rack-and-pinion focuser with 1:10 fine adjustment allows precise focusing, even with heavy imaging equipment. The system is compatible with electronic focusers such as the ZWO EAF. The telescope supports a wide range of cameras, including full-frame, DSLR, APS-C, mirrorless, CMOS, and CCD models. Included adapters (M48, M54, M68) provide flexible connectivity, with optional T-adapters available for major camera mounts.

A Losmandy-style prism rail is included for stable mounting, along with a sturdy carrying handle that can also support William Optics finders or guidescopes. The package also includes a Bahtinov focusing mask and a protective carrying case.

Optical Specifications

• Design: Refractor, Apochromat

• Lens system: Quadruplet with integrated corrector (7 elements)

• Glass material: OHARA FPL-53

• Aperture: 181 mm

• Focal length: 998 mm

• Focal ratio: f/5.5

• Resolving power: 0.76

• Limiting magnitude: 12.3

• Light gathering capacity: 670

• Maximum useful magnification: 362x

• Fully corrected image field: 55 mm

• Coating: SMC multi-coating

• Internal stray light baffles: Yes

Tube and Construction

• Tube weight: 15 kg

• Tube length: 1496 mm

• Carrying length: 1231 mm

• Dew shield: Yes

• Color: White

Focuser and Connectivity

• Focuser type: 3.7" rack and pinion

• Fine focusing: 1:10 reduction

• Rotatable focuser: Yes

• Eyepiece connection: 2"

• Camera adapter included: M54

• Additional adapters included: M48, M68

• Ring clamp: Yes

Mounting

• Type: OTA (Optical Tube Assembly only)

• Mount included: No

• Prism rail: Losmandy-style

Included Accessories

• Bahtinov focusing mask

• Carrying handle

• Carrying case

• Integrated corrector

Recommended Applications

• Astrophotography: Very good

• Nebulae and galaxies: Yes

• Moon and planets: Yes

• Solar observation: Only with appropriate solar filter

• Nature observation: Not recommended

Recommended For

• Advanced users: Yes

• Observatories: Yes

• Beginners: No