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The AP 51/250 refractor is a remarkable blend of compactness, affordability, and exceptional optical performance, making it a versatile choice for both astrophotography and nature photography enthusiasts. At its core, this refractor features a Petzval design, comprising four elements arranged in three groups, utilizing premium FPL53 and FPL51 glass. The result is a vivid, color-corrected image field with a generous diameter of over 44 mm, perfectly suited for full-frame cameras.

Thanks to its fast focal ratio of f/4.9, this telescope enables shorter exposure times, enhancing your imaging capabilities.

When it comes to camera connection, the AP 51/250 boasts an M48 thread, and you can easily find the appropriate T2 adapters among our recommended accessories. Focusing is a breeze with the helical mechanism, allowing you to effortlessly adjust even when using heavier cameras.

The included 110mm long dovetail bar provides three versatile connection options: screw connection with a photo thread, Arca Swiss, or Vixen standard fittings. With these choices, you can seamlessly attach this telescope to a wide range of photo tripods, mounts, or astronomical setups.

Notably, the package goes the extra mile by including a protective nylon carrying case and a specially designed Bahtinov mask built into the lens cap. This mask proves invaluable for precise focusing during your photography sessions.

The RedCat 51 is an ideal telescope for individuals who have a passion for both stargazing and wildlife photography, offering a versatile tool to capture the beauty of the night sky and the wonders of the natural world.



  • Type Refractor
  • Type of build APO
  • Aperture (mm) 51
  • Focal length (mm) 250
  • Aperture ratio (f/) 4.9
  • Resolving capacity 2.71
  • Limit value (mag) 10.3
  • Tube weight (kg) 1.5
  • Tube length (mm) 225
  • tube diameter (mm) 80
  • Focuser helical
  • Connecting threaded socket M48
  • Backfocus (mm) 59.7
  • Flattener n/a
  • Transport case included
  • Dew Shield included
  • Bathinow mask included

William Optics RedCat 51

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