William Optics RedCat 51 APO Refractor Telescope
 
Compact, Precision Optics for Astrophotography & Wildlife
The William Optics RedCat 51 is a versatile 51mm APO refractor designed for astrophotography, nature photography, and visual observation. Its fast f/4.9 focal ratio, 250mm focal length, and Petzval optical design make it an ideal choice for capturing deep-sky objects, wildlife, and landscapes with stunning clarity and minimal chromatic aberration.
 
Built with premium Ohara FPL53 & FPL51 synthetic fluorite glass, the RedCat 51 delivers high-contrast, tack-sharp images across a 44mm image circle. The calibrated helical focuser with 360-degree rotation allows for precise focusing and easy composition adjustments, while the built-in filter slot (48mm) enhances astrophotography flexibility. Its lightweight aluminum body is compact and easily mounts on tripods or equatorial mounts via its dual-purpose Arca-Swiss & Vixen dovetail base.
 
Condition: Excellent – Flawless Optics & Fully Functional
No marks, scratches, or cosmetic wear—pristine condition
Glass is flawless—free from dust, mold, or scratches
Includes Canon EOS T-mount 48mm adapter for seamless camera compatibility
All mechanical functions work perfectly, including the helical focuser & rotator
No box included
 
Key Features:
51mm Aperture, 250mm Focal Length (f/4.9) – Ideal for wide-field astrophotography & nature shots
Petzval Optical Design (4 Elements in 3 Groups) – Produces a flat field with virtually no chromatic aberration
Helical Focuser with Locking Mechanism – Ensures precise and stable focusing
360° Rotator with Degree Markings – Allows for perfect composition adjustments
Built-in 48mm Filter Slot – Supports standard astrophotography filters
Dual Arca-Swiss / Vixen Dovetail Base – Compatible with tripods & equatorial mounts
Lightweight & Compact – Weighs only 2.9 lbs (1.3 kg) and retracts to 8.3” (210mm) for portability
 
Why Choose the William Optics RedCat 51? If you’re a traveling photographer or astronomer, the RedCat 51 is your go-to. It’s a compact, pro-grade APO refractor that’s easy to mount and delivers top-notch optical performance. Whether you’re capturing nebulae, galaxies, or distant wildlife, it gives you razor-sharp, distortion-free images with spot-on color accuracy—ideal for serious creators on the move.
 
Frequently Asked Questions:
Can I use this as a telescope for visual astronomy?
Yes! By adding a diagonal and eyepiece, the RedCat 51 functions as a high-quality refractor telescope.
What cameras are compatible with this model?
This one includes a Canon EOS T-mount (48mm adapter), but the RedCat supports Nikon, Sony, Pentax, and Micro 4/3 cameras with the appropriate T-ring (not included).
Is this telescope good for deep-sky astrophotography?
Yes! With its flat-field Petzval design and 44mm image circle, it is perfect for capturing nebulae, galaxies, and wide-field star clusters.