The most famous travel astrograph, now with internal focuser
The William Optics RedCat 51 WIFD is the latest version of the world's most famous compact astrograph. The fast f/4.9 optics allow for short exposures, and the image remains sharp to the edges, even on a full-frame camera.
Petzval optics plus WIFD focuser
The four-element Petzval system with FPL53 and FPL51 glass provides a flat, color-pure image without a separate flattener: stars remain round and sharp, saving you time on post-processing. The internal WIFD focuser maintains constant balance and prevents sagging under camera weight. The Bahtinov mask is integrated into the lens cap.
In the box
- RedCat 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 (for the Cat 51 WIFD) do you also use the RedCat visually and for nature observation with an upright image. 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 a proven, color-pure astrograph that fits on any star tracker. Not for: Those primarily interested in visual observation; this is a photography tube. The ZenithStar line is more versatile.
Specifications
| Optical design | Apochromat, four-lens Petzval (FPL53 and FPL51) |
| Opening | 51 mm |
| Focal length | 250 mm |
| Opening ratio | f/4,9 |
| Focuser | WIFD (intern) |
| Field of view | Flat to full-frame |
| Focus assist | Integrated Bahtinov mask |
| Attachment | Arca-Swiss and Vixen-Style |
| Execution | OTA (loose tube) |
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.
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