REDCAT 51 II-U F/4.9 APO REFRACTOR

Click here to check out Alan Dyer's review of the RedCat 51 from Sky & Telescope magazine!

New version II-U including redesigned tilt adapter! Product photos are of the previous version II.

The William Optics RedCat 51 Version II-U is a fast apochromatic petzval refractor optimized for widefield astrophotography. Affordable, small and lightweight, the RedCat is perfect for traveling and on-the-go imaging.

With a fast focal ratio of f/4.9 and a focal length of 250mm, the RedCat 51 is perfect for capturing large deep space objects such as the Rosette nebula, the Pleiades, Eta Carina and more. The RedCat also excels as a telephoto wildlife lens.

The unique optical design includes the highest quality FPL-53 and FPL-51 synthetic fluorite glass for the best possible colour correction and a flat field across a full-frame sensor.

Note: the latest II-U version of the RedCat 51 is no longer able to be used visually, nor is it compatible with the RedCat 1.25" Erecting Prism (D-EP90-125-RC51-SL).

Focuser tension adjustment

Features

• Interchangeable camera mount
• Full-frame / APS-C compatible
• Apochromatic FPL-53 & FPL-51 lenses
• Anti-reflection multicoating
• Focuser tension adjustment ring (NEW)
• Super bright Bahtinov mask
• Dual Vixen / Arca-Swiss mounting plate
• Field rotator with markings for easy framing
• Premium indexed helical focuser
• Small and easy to store
• 48mm filter slot for standard 2" filters
• Modular mounting options
• Invertable sun shade / dew shield

• RedCat 51
• Patented Bahtinov mask
• 210mm dual dovetail
• Mounting rings
• Soft carry case