WILLIAM OPTICS REDCAT 61 WIFD

WILLIAM OPTICS REDCAT 61 WIFD

The William Optics 61 mm APO Astrograph is an excellent refractor for astrophotographers, and this RedCat version features the William Optics Internal Focus Design (WIFD). The RedCat 61 WIFD offers apochromatic, color-free performance, and is engineered to deliver outstanding full-frame image quality, pairing high performance with a visually striking design.

Constructed from durable aluminum alloy and finished with a protective anodized red coating, the RedCat 61’s body ensures strength and longevity. The matching red dew/sun shield can be attached when needed and reversed over the tube for compact storage without increasing the telescope’s length. A threaded red aluminum lens cap safeguards the optics when the telescope is not in use.

High-Quality Optics

A standout feature of the RedCat 61 is its premium optical system, making it ideal for astrophotography. Using a 4-element, 3-group Petzval design (2–1–1 configuration), the 61 mm RedCat incorporates FPL-53 glass in the front group, followed by a single middle element and a single rear element. This configuration provides a naturally flat image plane, eliminating the need for an external field flattener.
With Ohara FPL-53 synthetic fluorite glass and a Petzval layout, the telescope functions as a quadruplet refractor. Its apochromatic correction results in virtually zero chromatic aberration and full-frame edge-to-edge flatness. Because of the Petzval design, once the telescope reaches focus, the sensor spacing is automatically correct—no need to calculate back focus or adjust spacing.

William Optics Internal Focus Design (WIFD)

This advanced focuser incorporates the patented William Optics central focusing mechanism, using internal sliding optics that maintain alignment and prevent image shift. A built-in viewing window on the focuser displays a numbered scale for quick positioning reference.
Although the focusing system shows 30 mm of travel, the actual movement is 22 mm. A smooth rack-and-pinion mechanism delivers precise, fine focusing. The internal optical movement is sealed from environmental exposure and remains permanently aligned. By shifting the mass internally, the telescope achieves improved balance during imaging.

Wider Field of View

Compared to the William Optics RedCat 71, the RedCat 61’s shorter 300 mm focal length produces a significantly wider field of view. The example image (referenced at left) demonstrates the increased framing area. Users are encouraged to compare the difference using online field-of-view calculators. The expanded view is especially advantageous for capturing larger sky regions.

Cat Saddle Handle Bar

The included handle is a practical accessory for the RedCat 61 OTA. When attached to the supplied mounting ring, this Vixen-style handlebar offers a convenient way to carry the refractor. It also supports Vixen-style dovetails for guide scopes and guide rings, and is compatible with the William Optics UniGuide (not included).

REVIEW of WILLIAM OPTICS REDCAT 61 WIFD 👇