The William Optics Redcat 51 WIFD Review

Manufacturer: William Optics

Price: $898

I acknowledge your curiosity about the William Optics RedCat 51. It’s not just a telescope; for many, it’s a gateway to the cosmos. William Optics, a respected name in the realm of astronomy equipment, has crafted a piece that’s garnered attention for good reasons.

The RedCat 51 stands out due to its unique blend of portability, performance, and style. William Optics has made some huge improvements to this already excellent and wildly popular original model. This instrument is more than just optics; it’s designed with photographers in mind, offering a hassle-free pathway to capturing the night sky. What makes it especially inviting to astrophotography enthusiasts is its combination of accessibility and professional-grade quality.

Here are the basics: the RedCat 51 boasts a 250mm focal length and an impressive f/4.9 aperture. This means it can gather ample light, essential for observing and photographing celestial bodies. By design, it is perfect for wide-field imaging of large celestial objects, like many beautiful nebulae.

As a starting point, let’s explore the telescope that may well transform your star-gazing experiences into remarkable cosmic escapades.

Design and Build Quality: A Closer Look at RedCat 51

When examining the design of the William Optics RedCat 51, you instantly recognize its deviance from conventional telescopes. It boasts a patented Petzval design. Now, this is a notable feature because it corrects the field curvature that many photographers find frustrating in traditional optics. This enhances the sharpness and clarity across the entire field of view. But it is so much more. The company has patented a new internal focusing design called William Optics Internal Focus Design (WIFD). This new design improves on the original model helical focus, which made autofocus equipment difficult to use with this scope. The WIFD moves the focus mechanism internally, which not only makes this scope compatible with common autofocus equipment, like the ZWO EAF, but also eliminates sensor tilt and coma at the fringes of the image! The new design also eliminates the sag that can be produced by the addition of heavy accessories. But the scope also includes a sensor-tilt adjustment, just in case. The design is so successful that William Optics is incorporating it into its new telescope models.

Delving into the materials used, I find the aluminum housing robust yet remarkably lightweight, a testament to the thoughtful engineering that went into its creation. The finish is a sleek, red anodized look that not only protects the telescope but makes it stand out in the world of astrophotography gear. It really is a beautiful piece of equipment.

As for usability, if you’re an amateur astronomer or a traveling stargazer, you’ll appreciate its compact size. It’s small enough to fit in a backpack, making it a go-to scope for spontaneous night sky explorations or extended astro-adventures far from city lights. One of the downsides of the new focusing mechanism is that it makes the scope a bit heavier, increasing from 3.9 lbs. (1.8 kgs) to 5.2 lbs. (2.4 kgs) with accessories attached. But it is still very portable and the new design makes it well worth the slight extra weight.

How does the RedCat 51 stack up against the competition? It resides in a unique spot, offering premium features at a mid-range price of less than $1000. While there are certainly less expensive telescopes available, the quality of the RedCat 51’s optics and the precision of its manufacturing place it in a league of its own relative to other models in its price range. William Optics has a long history of producing quality gear at a reasonable price.

RedCat 51 Scope with Included Carrying Case

Optical Performance and Astrophotography

When I talk about the William Optics RedCat 51, one aspect I can’t help but highlight is its optical performance, which is truly a defining feature. Its apochromatic (APO) quadruplet Petzval lens system brings out sharp, clear images with minimal chromatic aberration, making it a worthy tool for capturing the night sky all across the 45 mm image circle, which is more than enough to cover a full-frame sensor.

A standout characteristic of this telescope is its fast focal ratio of f/4.9. This translates into shorter exposure times for astrophotography, allowing you to capture more detail in night sky objects even with limited time on clear nights. More detail with less waiting is a win in any astronomer’s book.

The RedCat 51’s ample field of view stands out in the market. It’s wide enough to frame large celestial objects like nebulae and galaxies, offering a splendid perspective of the cosmos. This feature ensures you get the best possible images, whether you’re a novice just starting or a seasoned hobbyist looking to step up your game.

Actual users of the RedCat 51 often share their awe-inspiring results on social media, and the feedback is overwhelmingly positive. Enthusiasts regularly praise the telescope for the clarity and quality of the images it produces, which is huge in such an exacting hobby as astrophotography, especially with the competition for quality gear at reasonable prices.

Like other William Optics refractors, the RedCat 51 comes with a Bahtinov mask in the cap to make achieving perfect focus a breeze if you don’t have an electric autofocuser (I still recommend getting one. It will make your life so much easier!).

Integrated Bahtinov Mask

Investing in Your Passion: Pricing and Available Accessories

In the realm of amateur astronomy, the choice of equipment is as crucial as the celestial wonders you aim to capture. The William Optics RedCat 51 has earned its stripes among stargazers, but a potential investment merits a careful look at its price and the accessories that can enhance its performance.

PRICE POINT: It may not be the cheapest option available, yet the RedCat 51 offers compelling features for its price. By striking a balance between cost and quality, it presents itself as a prime choice for serious astrophotographers who demand top-notch results without breaking the bank. In my opinion, you don’t want to go too cheap with refractors, and this scope is a no-brainer in terms of cost and quality.

The market for telescopes is vast, with options ranging from budget-friendly models to premium, high-end units. In this context, the RedCat 51 finds its place on the higher end of the mid-range spectrum. It’s a thoughtful investment, particularly for those who appreciate the nuances of astrophotography and celestial observation.

ACCESSORIES: To get the most out of the RedCat 51, consider investing in certain accessories. A stable tripod, for example, is non-negotiable for clear, crisp images. An equatorial mount can make tracking the night sky a breeze. Filters, extension tubes, and a camera adapter will further fine-tune your experience. For the ultimate setup, I recommend an autofocuser, like the ZWO EAF.


  • Superb Optics
  • M54 threads included, which are ideal for full-frame sensors
  • No sag WIFD focusing mechanism
  • Out-of-the-box compatibility with the ZWO EAF focuser.
  • Highly portable and lightweight
  • Great value for the price
  • Beautiful design


  • Only suitable for wide fields (not good for galaxies or small nebula)

What’s included?

  • RedCat 51 WIFD
  • Carrying Case
  • Bahtinov Cap
  • Dual Mounting Plate
  • M48 Cap
  • Mounting Ring Handlebar
  • Allen Key Set

Verdict: 5/5 Stars

When all is said and done, the value of RedCat 51 is measured not just in dollars and cents, but in the quality of the images it can produce and the enjoyment it brings to your hobby. Like any good investment, it’s about the returns. In this case, the returns are the breathtaking views of the cosmos, captured precisely as you envisioned them with perfect star images across the field. This new design of the very popular small refractor offers several advantages over the previous version.




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