William Optics AP 51/178 Apochromatic refractor MiniCat WIFD OTA

The smallest cat: 178 mm focal length at f/3.5

The William Optics MiniCat 51/178 WIFD is made for photographers who want to think big in a small format. With a focal length of 178 mm and an aperture of f/3.5, you can capture large sky fields: complete constellations, the Milky Way, and vast nebulae, with short exposures and low noise.

Six-element optical system with internal focusing

The six-element lens design keeps stars round and tight even into the corners, without a separate flattener. The internal WIFD focuser does not move weight externally, so your balance remains stable and your camera rotates without sagging. The Bahtinov mask is integrated into the dew shield for quick and precise focusing.

In the box

• MiniCat 51/178 Optical Tube with WIFD Focuser
• Integrated Bahtinov mask
• Dew cap
• Arca-Swiss and Vixen-Style dovetail
• Nylon tote bag

Featured accessories

A William Optics UniGuide 32mm Guidescope (159 euros) completes the setup for long exposures. William Optics' M48 camera adapters are available for common mounts; choose the variant for your camera.

For whom yes, for whom no

For: Astrophotographers who want to capture wide sky fields with a lightweight travel setup or star tracker. Not for: those seeking image scale for smaller nebulae or galaxies; look to the RedCat 71 or Cat 91 class.

Specifications

Unsure about the right tube for your camera and mount? The telescope selection aid helps you choose. Also view all Refracting telescopes and the full range of William Optics.