Celestron - Off-Axis Guider - 93648

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  • The Celestron Off Axis Guider is the most accurate way to guide – improved accuracy compared to using a separate guide scope

  • 12.5 mm multi-coated prism with aluminized backing for maximum reflectivity and illumination to the autoguider

  • Fixed-orientation helical focuser for easy, smooth and accurate autoguider focus

  • 48mm clear aperture supports full frame cameras without vignetting

  • Includes adapters with the correct spacing for DSLR cameras, Nightscape CCD and other popular astroimaging cameras

  • Ideal for Schmidt- Cassegrain and EdgeHD telescopes

SKU: CEL-93648
Manufactured by:

Product Description

The Off-Axis Guider is an essential astroimaging accessory for long focal length telescopes that require the most accurate guiding possible. The Celestron Off-Axis Guider uses a prism to intercept a small portion of the telescope’s focal plane (outside the field of view of the main imaging camera) to locate a guide star. Any movement seen by the guide star will be the exact same movement seen by the imaging camera. Guiding this way will correct for tracking errors, as well as opto-mechanical errors or flexure. The result: better astroimages with pinpoint round stars.

Off-Axis Guiders have been around for a long time, but typically pose three main challenges:

  • Finding a guide star from the far edges of the telescope’s focal plane can be difficult, considering the small field of view and sometimes less-than-ideal illumination.
  • Getting both imaging camera and autoguider to reach focus with one another is time consuming and sometimes requires experimentation.
  • Additional spacers and adapters are usually required for your particular camera, telescope, and autoguider, which adds to cost and complexity.
  • Celestron's Off-Axis Guider addresses these challenges by:

  • Providing a large 12.5mm prism that can be adjusted to move closer to the center of the telescope’s focal plane, depending on the size of the imaging camera. This results in brighter guide stars, with the help of the large prism to fully illuminate the autoguider sensor.
  • Featuring a high-quality, fixed-orientation Helical focuser. This provides extremely smooth and accurate focus of the autoguider without changing (or twisting) the autoguider camera orientation.
  • Including all the needed spacers and adapters are included for most common imaging configurations, including DSLR cameras, Nightscape CCD cameras, and more. The following adapters are included: SCT/EdgeHD, female M48, female M42 (T-thread), male M48, male M42 (T-thread), 3 T-thread spacers

    Additonal Specifications

    Helical Focuser Travel: 8mm
    Telescope Connection: M42 T-thread, M48, and SCT/EdgeHD
    Autoguider Connection: M42 T-thread, and standard 1.25" adapter
    Camera Connection: M42 T-thread, and M48


    Name Celestron - Off-Axis Guider - 93648
    Manufacturer Celestron
    Model CEL-93648
    UPC 050234936484


    Review and collect 50 points.
    Review by:
    Big improvement over other oag's owned by my friends. Larger adjustable prism and all metal construction a big plus. Instructions could be more detailed for those of us without experience using off-axis guiders. (Posted on 5/1/2015)
    Review by:
    SCT has a large back focus, so this OAG, for SCT, has a rich design.
    Large prism. Double rotating device arrived back and forth. Smooth helicoid for guide CCD.M48 adapter for the camera. Very sturdy body.
    I'm using the OAG with reducer. Can be adjusted out of the prism, so it has gained sufficient viewing. There is no need to look for guide star. The image of exposure 3 minutes to try to 20 sheets composite but never deviated 0.2 pixel. It is 1/20 of when using the guide telescope.
    (Posted on 2/25/2015)
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