William Optics AP 51/250 Apochromatic Refractor SpaceCat WIFD OTA

The same Cat optics in its own design

The William Optics SpaceCat 51 WIFD It shares its optical heart with the RedCat 51: the same fast f/4.9 Petzval system, the same internal WIFD focuser, but in the distinctive SpaceCat version. You get a bright, flat image that remains sharp all the way to the corners, even on full-frame.

Ready for the tracker

The Petzval design makes a separate flattener redundant, so your setup stays light and simple: tube, camera, tracker, done. The Arca-Swiss/Vixen dovetail bar fits directly onto photo tripods and star trackers, and the integrated Bahtinov mask makes focusing exact and fast.

In the box

• SpaceCat 51/250 optical tube with WIFD focuser
• Integrated Bahtinov mask
• Arca-Swiss & Vixen-Style Prism Rail
• Nylon tote bag

Featured accessories

With the William Optics 90 degree zenith prism (version for the Cat 51 WIFD) the SpaceCat can also be used visually. 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 the proven Cat 51 optics and prefer the SpaceCat version's aesthetics or appreciate the price advantage. Not: those looking for a longer focal length for smaller objects; the RedCat 71 or Cat 91 class provides a larger image scale.

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.