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Celestron 45-Degree Erect Image Diagonal
Celestron 45-Degree Erect Image Diagonal

Celestron 45-Degree Erect Image Diagonal

by Celestron
SKU CEL-94112-A
$45.00 - $45.00
$45.00
$45.00 - $45.00
$45.00
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  • Corrects image orientation for terrestrial viewing
  • Produces right-side-up and left-to-right correct images
  • Comfortable 45-degree viewing angle for daytime use
  • Compatible with refractor and catadioptric telescopes (SCTs, Maks)
  • Standard 1.25" barrel size
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Celestron 45-Degree Erect Image Diagonal

    The Celestron 45-Degree Erect Image Diagonal is the essential accessory for turning your astronomical telescope into a high-power daytime spotting scope. This diagonal uses an Amici prism to provide a correctly oriented, right-side-up and left-to-right image, making it indispensable for terrestrial observation, all backed by a 2-Year Warranty.

    Correcting Your View for Terrestrial Observation

    A standard star diagonal renders images upside-down or mirrored, which is disorienting for terrestrial viewing. The Celestron 45-Degree Erect Image Diagonal solves this by reorienting the light path. Simply swap it with your telescope's standard diagonal to see the world as it is—right-side up and dimensionally correct—making it easy to track birds, boats, or distant landscapes.

    The 45-Degree Advantage for Refractors and SCTs

    The 45-degree viewing angle is specifically designed for comfort during terrestrial observing, when your telescope is often aimed horizontally. This diagonal is fully compatible with any refractor or Schmidt-Cassegrain (SCT) telescope that uses a standard 1.25" focuser or visual back.

    • Amici Prism Design: Ensures a fully corrected image, unlike standard mirror diagonals that only correct one axis.
    • Daytime Comfort: The 45-degree angle reduces neck strain when observing subjects on or near the horizon.
    • Important Limitation: This diagonal is not intended for Newtonian reflector telescopes. The optical design of a Newtonian will prevent this accessory from producing a fully corrected image.

    45-Degree Erect Image Diagonal vs. Standard 90-Degree Star Diagonal

    While a 90-degree star diagonal is ideal for astronomy where the telescope points high into the sky, it's less practical for terrestrial use. The key difference lies in the image orientation and viewing angle.

    • Image Orientation: A standard 90-degree diagonal typically produces an image that is right-side up but reversed left-to-right. The 45-degree erect image diagonal corrects both axes.
    • Viewing Angle: The 45-degree angle of this diagonal is far more natural and comfortable for horizontal viewing than the steep 90-degree angle of a star diagonal.

  • Why do I need a 45-Degree Erect Image Diagonal for birdwatching with my SCT?

    Without an erect image diagonal, the view through your Schmidt-Cassegrain telescope will be either upside-down or mirror-reversed. This makes tracking a moving bird nearly impossible. The Celestron 45-Degree Erect Image Diagonal corrects the view to be right-side up and left-to-right correct, just like looking through binoculars.

    Can I use the Celestron 45-Degree Diagonal for astronomy?

    While you can, it's not ideal. The Amici prism design has a slight ridge in the center that can cause a faint spike on very bright objects like planets or bright stars. For the highest-contrast astronomical views, a dedicated 90-degree mirror or prism star diagonal is recommended.

    Will this 45-Degree Erect Image Diagonal work on my Newtonian reflector telescope?

    No. Due to the optical design of Newtonian reflectors, this diagonal will not produce a fully corrected image. The image orientation will still be rotationally off, and you may not be able to reach focus. This accessory is designed exclusively for refractors and catadioptric telescopes like SCTs and Maksutov-Cassegrains.

    Is the Celestron 45-Degree Diagonal hard to install on my telescope?

    Installation is simple. You just remove your existing 1.25" diagonal from the telescope's focuser or visual back by loosening the thumbscrews, and then insert the 45-Degree Erect Image Diagonal in its place and tighten the screws. It takes only a few seconds.

    What's the main benefit of the 45-degree angle over a 90-degree angle?

    For terrestrial viewing, your telescope is typically horizontal. The 45-degree angle allows you to look down into the eyepiece comfortably. A 90-degree angle would force you to bend over at an awkward angle to see through the eyepiece when the telescope is aimed at the horizon.

    I have a Celestron refractor. Will this diagonal allow me to read a sign across the street?

    Yes, absolutely. A standard diagonal would show the text reversed as if in a mirror. The Celestron 45-Degree Erect Image Diagonal will present the text correctly, making it readable. This is a perfect example of what this accessory is designed for.

  • Viewing Angle 45 Degrees
    Prism Type Amici Roof Prism
    Image Orientation Erect and Correct Left-to-Right
    Barrel Size 1.25"
    Compatibility Refractors and Schmidt-Cassegrain / Maksutov-Cassegrain Telescopes
    Warranty 2-Year Warranty

    • Celestron 45-Degree Erect Image Diagonal - 1.25"

      × 1

    • Dust Caps

      × 2

  • Celestron 2-Year Warranty