Astronomy Specialist

REDCAT 51 II-U F/4.9 APO REFRACTOR

$878.00 USD
SKU: WO-L-RC51II
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William Optics

Apochromatic Petzval quadruplet

51 mm

f/4.9

250 mm

1.8 kg


 

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



 

 

Optical design

Apochromatic petzval (4 elements in 3 groups)

Objective diameter

51 mm

Focal length

250 mm

Focal ratio

f/4.9

Image circle

44 mm

Material

Anodized aluminium alloy

Mount attachment

 210 mm Dual Vixen-style / Arca-Swiss dovetail bar

Focuser

Indexed manual helical focuser

Camera connection

M56 x 0.75, M48 x 0.75, optional T-Mounts

Backfocus

59.7 mm from M48 thread

Tube weight

1.8 kg

Tube length

225 mm (fully retracted), 305 mm (fully extended)

Tube diameter

80 mm

SKU

WO-L-RC51Ix

 

 

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

 


 

Eta Carina with RedCat 51, Nikon D800 by Wang Wei Hao.
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REDCAT 51 II F/4.9 APO REFRACTOR.

REDCAT 51 II-U F/4.9 APO REFRACTOR

$878.00 USD

Optical design

Apochromatic Petzval quadruplet

Image circle

Focal ratio

f/4.9

Aperture

51 mm

Focal length

250 mm

Optical thickness

Threads

Cooled

Colour or Mono

Pixel size

Sensor dimensions

Resolution

Sensor diagonal

Quantum efficiency

Read noise

Fullwell capacity

Bit depth

FPS

Camera backfocus

Filter size

Filter size

Bandpass (FWHM)

Bandpass (FWHM)

Glass thickness

Mount type

Payload capacity

Latitude range

Dovetail saddle

Slew speed

Encoders

Periodic error correction

Counterweight shaft

Azimuth adjustment range

Internal diameter

Illuminated diameter

Compatible telescope external diameter

Weight

1.8 kg

Length

Width

Height

View product