William Optics MiniCat 51 WIFD f/3.5 Petzval Refractor Telescope - Red

William Optics MiniCat 51: the Perfect Wide-Field Astrophotography Telescope

Building on the massive success of the RedCat 51 series, William Optics has now introduced the MiniCat 51! Weighing in at  just 5 lbs (2.3 kg) and featuring a small footprint with a full frame image circle, this tiny scope is designed for producing jaw-dropping wide-field astrophotography images.

Gather Light Twice as Fast as the RedCat 51

The RedCat 51 series has kept one thing constant: the f/4.9 focal ratio. This all changes with the MiniCat 51. It now features a blazing fast f/3.5 focal ratio, meaning it can gather the same amount of light in less than half the time as the RedCat 51!

This faster focal ratio lets you focus more on capturing your target in staggering detail. Of course with the focal ratio change also comes a change in focal length: the focal length is reduced from 250mm down to 178mm. This focal length is ideal for capturing large widefield views of the night sky.

Same Full Frame Image Circle

Despite a faster focal ratio, the MiniCat 51 retains its 43mm image circle from the RedCat 51. William Optics was able to achieve this by using 6 elements for this scope instead of 4, with two of them being super ED elements in the familiar Petzval design. As usual, William Optics has spared no quality components even in the smallest scope they've ever produced.

Correctable Corner Imperfections

Due to the nature of the MiniCat's fast aperture optical design, edge stars may not be as round as with other RedCats. However, tests show it still outperforms conventional lenses. With abberation correction software like BlurXTerminator, peripheral distortions can be perfectly corrected on APS-C sensors, while Full Frame may need some fine-tuning for even better results.

Precision Imaging Adjustment

Tilt Adjuster: The built-in tilt adjuster makes it easy to correct camera sensor tilt issues.

Camera Angle Rotator: Corrects any angular discrepancies and get the perfect angle on your images.

Integrated Bahtinov Mask

The patented bahtinov mask is laser engraved on high definition and stable optical PMMA and enhances astrophotography experience with quick and accurate adjustments.

WIFD Focuser: Ideal for Serious Imaging

Like many telescopes William Optics has produced recently, the MiniCat 51 features the same patented WIFD focuser design. This design moves all lens elements internally to achieve focus, meaning there is no drawtube to rack in or out — great for retaining a small profile travel scope. The WIFD focuser is compatible with the ZWO EAF and other popular autofocus designs out of the box, which is a welcome feature on a scope this small.

Many widefield imagers have had to resort to using camera lenses like the Rokinon 135mm (also known as the Samyang 135mm) which have a helical focuser. This makes using an autofocus mechanism difficult and costly as you have to buy adapters and piece it together. The MiniCat 51's design makes it super easy to say goodbye to fussing with third-party autofocus kits.

Important Note about Reaching Focus with the MiniCat 51: Being a Petzval design, the MiniCat 51 doesn't have a fixed back focus point. However, However, to reach focus, your setup should have a backfocus between 30mm and 58mm. The drawtube has a 28mm travel, and if the backfocus is shorter than 30mm or longer than 58mm, focus cannot be achieved.

The WIFD focuser design relocates the focuser to the center of the telescope, addressing the issue of tube tilt caused by the weight of accessories and cameras.

Rotator, Dovetail Bar, & Saddle Handle Included

The MiniCat 51 comes standard with a number of accessories to make imaging a breeze. It comes with a dual Vixen-style and Arca-Swiss dovetail bar, mounting ring, a CAT series carrying handle with mount for a guide scope on top, and a marked 360-degree rotator on the back to allow you to dial in the perfect framing.

William Optics MiniCat 51 Specifications:

• Lens Type: 6-Element Petzval Design
• Focal Length: 178 mm
• Diameter: 51 mm
• Aperture: f/3.5
• Image circle: 43.2 mm
• Back focus range:  30mm - 58mm
• Focuser: WIFD R&P Focuser, Compatible with EAF
• Adapter Included: Tilt Adjuster, Rotator, M54 → M48 Adapter
• Optional Flattener: No Flattener Required
• Camera Format: Full Frame (Compatible), APS-C (Recommended), M4/3
• Tube Length: 210 mm
• Dew Shield OD: 80mm
• OTA Weight: 1.67 kg / 3.68 lbs
• Total Weight: 2.29 kg / 5.05 lbs