Learn about the William Optics Redcat71 telescope

In recent years, there has been a shift in imaging methodology towards instruments specifically designed for astrophotography. The William Optics RedCat71 from First Light Optics is one such instrument that aims to meet the needs of astrophotographers. This magazine-style scientific article will provide an analysis of the RedCat71 and its features.

The first thing that catches the eye is the RedCat71’s stunning all-red livery. Its tube length is a compact 335mm, making it highly portable. The telescope comes in a durable, padded nylon carry-case, which is ideal for airline hand-luggage.

A remarkable feature of the RedCat71 is that it cleverly incorporates the Bahtinov mask into the lens cap. This accessory is essential for achieving sharp focusing in astrophotography. The telescope also boasts a large helical focuser barrel with a rubberised surface that’s both tactile and non-slip. The rotational tension on the focuser barrel is controlled by the dew tube, which acts as a friction clamp.

The RedCat71 offers a generous 360-degree rotating M54 thread, along with M54 and M48 adaptors. These adaptors include a cell for deploying 48mm filters. They also feature a tilt mechanism for precise adjustment to match the imaging plane, catering to the needs of even the most demanding astrophotographers.

It is worth noting that while the RedCat71 is designed primarily for astrophotography, it does not come complete with photographic adaptors. This may be a downside for users who are new to imaging and do not already possess these adaptors.

However, despite being primarily designed for astrophotography, the RedCat71 can also be used for visual astronomy with some modifications. While attempting to use a star diagonal with the telescope, it was found that the eyepieces were too far beyond focus. This indicated that visual use might be challenging due to insufficient back-focus. However, by using an alternative method of attaching eyepieces, it was possible to achieve focus and observe the Moon with impressive detail.

In terms of optics, the RedCat71 employs a new apochromatic Petzval design with four elements in three groups. This configuration promises a wide, flat field with a 45mm imaging circle, making it suitable for sensors up to DSLR full-frame size. Testing the telescope’s native optics revealed a symmetrical and evenly distributed defocused diffraction pattern, indicative of high-quality optics.

The RedCat71’s focal length is a compact 348mm, resulting in very wide imaging fields. Testing the telescope’s imaging capabilities using a full-frame DSLR revealed no discernible difference in image quality between the centre and edge of the field. This demonstrates the telescope’s ability to deliver sharp and crisp images across the entire field of view.

When it comes to deep-sky astrophotography, the RedCat71 truly shines. With its wide field of view, it’s capable of capturing large celestial objects in their entirety. The reviewer had no trouble capturing the entire Veil Nebula, which spans three degrees, in a single image. The RedCat71 also proved to be highly capable when imaging the North America Nebula and M13 in Hercules.

To wrap it up, the RedCat71 from William Optics is an excellent instrument for astrophotography. Its compact size and portable design make it ideal for travel. The telescope’s attention to detail and engineering finish are evident throughout, from its all-red livery to its large helical focuser barrel. While the quick-start guide may be lacking in instructions for beginners, the telescope itself delivers exceptional performance.

Whether used for deep-sky astrophotography or visual observing with some modifications, the RedCat71 proves to be a versatile and capable instrument. Its apochromatic Petzval design and wide field of view produce sharp and crisp images, capturing even the smallest details in celestial objects. The RedCat71 is a valuable addition to any astrophotographer’s toolkit.

Overall, the RedCat71 offers excellent quality and performance for its price point of £1,599. Whether you are a seasoned astrophotographer or a beginner looking to explore the wonders of the night sky, the RedCat71 is well worth considering.

By Steve Ringwood