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William Optics WhiteCat 51 APO f/4.9 Refracting Telescope - Limited Edition - L-RC51W


William Optics has discontinued the WhiteCat 51 APO f/4.9 Refracting Telescope, and we are out of stock. Here is a link to the William Optics Cat Series Refractors we carry at High Point. Hopefully, you can find a proper replacement in this selection. If we can be of further assistance, please don't hesitate to call us at 1-800-266-9590 or send an email, and we will be happy to help you. Thank you!

William Optics WhiteCat 51 APO f/4.9 Refracting Telescope

Whether you want to image wildlife or the night sky, this 51 mm refractor from William Optics is the perfect companion for the traveling photographer and astronomer!

The WhiteCat has an aperture of 51 mm, a focal length of 250 mm and a fast f/4.9 focal ratio. It is also lightweight and easy to transport!

This William Optics Cat Series scope comes with 48 mm threads and is compatible with a variety of wide Canon to Nikon, Sony E to Pentax, or Micro 4/3 T-mounts.

You can also put a diagonal and eyepiece on the back for spectacularly sharp, high contrast images of both terrestrial and celestial targets. The WhiteCat mounts on a photographic tripod or an equatorial mount with the reversible base that has Arco-Swiss mounting on one side and a standard Vixen dovetail on the other.

WhiteCat Optics

The William Optics WhiteCat 51 optics are made of Ohara FPL53 & FPL51 synthetic fluorite glass. This glass provides high contrast and sharp results when used for both visual and photographic applications. The APO performance means you’ll have virtually zero chromatic aberration. The Petzval design, which consists of four elements in three groups, also known as a Quad, produces a full frame flat field, with a image circle of 44 mm.

OTA Design

Let’s start at the front and work our way back! The WhiteCat body is made of a strong aluminum alloy and is anodized a beautiful red for strength and durability. A matching dew/sun shield can be attached when needed and then inverted to store the lens without the additional length the dew shield provides. An aluminum threaded cap protects the optics whenever the WhiteCat is not in use.

In the middle of the WhiteCat 51, you will find a nicely designed ring mount that attaches to the reversible base and wraps securely around the body of the lens. A red anodized knob allows you to loosen the ring enough to fully rotate the WhiteCat 51, and of course, it is also used to lock the ring in place. The “ring” has a flat section that has two 1/4-20 holes spaced far enough to allow the addition of a red dot finder, microphone, or other compatible accessories. Included with this Cat refractor is a Bahtinov Mask for focusing assistance during astrophotography, a M48 camera mount, and a soft carry case. Aluminum covers are also included for the front and back of the telescope.

Calibrated Helical Focuser with 360-Degree Rotator

The helical focuser with a focusing index on the WhiteCat has a focus tension ring that allows you to lock focus or just increase or decrease the drag to your liking. A field rotator is included with this 250 mm lens as well, and every degree is plainly marked…all 360 of them! William Optics says they were inspired by luxury watches when they designed this rotator, but what it means to you is mosaics of large celestial objects or sections of the sky will be much easier!

A filter slot is built into the OTA just after the rotator and accepts 48 mm filters, and the back of the WhiteCat is fitted with M48 threads. Attach a full-frame (M48) M 4/3, Nikon, Canon, Sony, or Pentax T-ring to the threads and use your DSLR to produce beautiful images. Or, attach a diagonal and eyepiece and turn this 250 mm f/4.9 beauty into a telescope or spotting scope.

Includes These Accessories

You will also receive a Bahtinov Mask for focusing assistance during astrophotography (that might give you a hint as to why the Cat’s whiskers look like they do…just look at the threaded cap), the M48 camera mount (T-ring mentioned above not included) and a soft carry case. Aluminum covers are also included for the front and back of the telescope.

William Optics WhiteCat 51mm Petzval APO Refractor Specifications

  • Telescope Series: William Optics Cat
  • Optical Design: Refractor
  • Refractor Design: Apochromat (APO)
  • Number of Refractor Elements: 4
  • Aperture: 2" (51 mm)
  • Focal Ratio: f/4.9
  • Focal Length: 250 mm
  • Focuser Style: Helical
  • OTA Length - Retracted: 8.3" (210 mm)
  • OTA Weight: 2.9 lb.
  • Image Circle Size: 44 mm