William Optics Apochromatic refractor AP 51/178 MiniCat WIFD OTA (84908)

The Cat Series Astrographs: Easy-to-Use Optics for Nature and Astrophotography

The Cat series astrographs, available in the RedCat and SpaceCat color variants, are designed for simplicity and high performance in nature observation and astrophotography.

At the core of these optics lies a Petzval design, featuring four lenses in three elements. This design provides a color-corrected and flat field of view without the need for an external field flattener. Unique features include a field rotator with an integrated filter holder, enabling seamless camera rotation, and a tilting collimator to achieve precise alignment of the image plane with the camera sensor.

For ease of focusing, the patented William Optics Bahtinov mask is integrated directly into the lens dust cap, allowing users to quickly and accurately focus on bright stars.

Specifications Overview

Optics:

• Type: Refractor (Apochromat)
• Aperture: 51 mm
• Focal Length: 178 mm
• Aperture Ratio: f/3.5
• Lens Design: Quintuplet with OHARA FPL-53 glass
• Field of View: Fully corrected up to 43.2 mm

Tube Construction:

• Material: Aluminium
• Weight: 1.67 kg
• Length: 274 mm
• Coating: Multi-coated optics
• Dew Cap Diameter: 80 mm

Focuser:

• Type: Internal, rotating
• Threaded Socket: M48
• Backfocus: 59 mm

Mount:

• Type: OTA (Optical Tube Assembly) with azimuthal mounting compatibility

Included Accessories:

• Dew shield
• Carry case
• Integrated Bahtinov focus mask
• Prism rail compatible with Arca-Swiss & Vixen-Style mounts
• Camera tripod thread

General Features:

• Series: Cat
• Color: Red
• Applications: Excellent for astrophotography, moon, planetary, nature, and nebulae/galaxies observation (not suitable for solar observation without proper filtering).

Recommended Usage:

• Beginners: Not recommended
• Advanced Users: Yes
• Observatories: Not recommended