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The William Optics UltraCat 56 is now in stock at Khan Scope Centre.
William Optics UltraCat 56
f/4.8 WIFD Petzval APO Refractor
$1,949 CAD
✓ IN STOCK
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Why the UltraCat 56?
The UltraCat series represents William Optics' evolution beyond the popular RedCat line. The key difference is a 5-element Petzval design (versus 4 elements in the RedCats), which delivers sharper stars, better aberration control, and a larger fully-illuminated image circle.
No flattener. No backspacing calculations. With most imaging refractors, you're buying a separate field flattener, measuring 55mm backspacing, and adding spacers until everything lines up. The UltraCat's flat field is inherent to the optical design—if your camera reaches focus, the entire frame is in focus. That's one less variable to troubleshoot.
Internal focusing that stays balanced. The WIFD system moves the optics inside the tube rather than extending a drawtube with your camera attached. This eliminates drawtube sag (particularly important with heavier imaging trains), prevents vignetting, and keeps your balance point constant. You won't need to rebalance after focus adjustments.
Built-in tilt correction. As sensors get larger and pixels get smaller, sensor tilt has become increasingly visible in corner star shapes. Most imagers solve this with shimming or aftermarket tilt plates. The UltraCat includes William Optics' Sensor Tilt Xterminator—a 4-knob seesaw system that lets you dial in precise alignment without removing your camera.
Who Is It For?
New imagers looking for a wide-field setup that works out of the box without the learning curve of flattener selection and backspacing.
Experienced imagers who want a compact, travel-friendly rig for dark site trips, Milky Way season, or a second scope dedicated to wide-field mosaics.
Full-frame camera owners who need optics that actually illuminate their entire sensor without vignetting or edge degradation.
Portable setup enthusiasts — at 2.56 kg with a 269mm focal length, this scope pairs well with lighter mounts like the ZWO AM5, iOptron HEM27, or even robust star trackers.
What Can You Capture?
The 269mm focal length at f/4.8 is ideal for large-scale targets: the Orion Nebula complex, North America and Pelican Nebulae, the full Veil Nebula, Andromeda Galaxy with its companion galaxies in frame, wide Milky Way star fields, and expansive molecular cloud regions like the Cepheus flare or Rho Ophiuchi.
Specifications
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Optical Design:
5-Element Advanced Petzval APO
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Aperture:
56mm
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Focal Length:
269mm
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Focal Ratio:
f/4.8
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Image Circle:
50mm (Full Frame & Medium Format)
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Focuser:
WIFD Rack & Pinion (EAF Compatible)
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Weight:
2.56 kg
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Tube Length:
296mm – 348mm
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What's in the Box
UltraCat 56 OTA • Sensor Tilt Xterminator with integrated Rotator • M68 to M48 Adapter • Rear Dust Cap • Objective Cap with Bahtinov Mask • Handle Bar with Vixen-style guidescope dovetail • 210mm Dual-sided Dovetail Plate (Vixen & Arca-Swiss) • Temperature Gauge • Allen Keys
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Financing Available: Affirm and RBC PayPlan options at checkout.
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Clear skies,
Ray & The Khan Scope Team
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