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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader Adapter - 2" NexStar 4 (C90)/ETX
Baader Adapter - 2" NexStar 4 (C90)/ETX

Baader Adapter - 2" NexStar 4 (C90)/ETX

by Baader Planetarium
SKU BAA-2958500
$79.00 - $79.00
$79.00
$79.00 - $79.00
$79.00
Price Match Policy!
  • Connects Celestron C90/NexStar 4 and Meade ETX telescopes to 2" accessories
  • Enables the use of 2" diagonals for wider true fields of view
  • Accepts 2" eyepieces for low-power, rich-field observing
  • Provides a rigid, single-piece connection for astrophotography
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Baader Adapter - 2" NexStar 4 (C90)/ETX

    The Baader 2" NexStar 4 (C90)/ETX Photo Adapter directly addresses the primary limitation of these popular Maksutov-Cassegrain telescopes: their small accessory port. This single component replaces the standard visual back, establishing a full 2-inch aperture and a rigid, flex-free connection for modern diagonals, wide-field eyepieces, and larger camera systems.

    Unlock 2" Diagonals and Eyepieces on Your C90/ETX

    While Celestron C90, NexStar 4, and Meade ETX telescopes are known for their sharp, high-contrast optics, their potential is often limited by a 1.25" visual back. This adapter opens up your compact telescope to the world of 2" accessories, allowing you to achieve significantly wider true fields of view. By pairing your scope with a 2" diagonal and low-power 2" eyepieces, you can frame large targets like the Andromeda Galaxy (M31) or the Pleiades (M45) in a single view.

    A Rigid 2" Foundation for Astrophotography

    As a dedicated photo adapter, this component creates a solid, secure link between your telescope and your imaging equipment. Stacking multiple smaller adapters to connect a camera introduces potential flexure and tilt, which can ruin an exposure. The Baader 2" adapter provides a single, robust connection point, ensuring your camera remains perfectly aligned with the telescope's optical axis throughout a long imaging session.

  • What is the main benefit of using the Baader 2" Adapter on my Celestron C90?

    The primary benefit is upgrading your telescope from the restrictive 1.25" accessory format to the much larger 2" standard. This allows you to use 2" diagonals and wide-field eyepieces, dramatically increasing the true field of view for observing large deep-sky objects.

    Will this adapter let me use 2" eyepieces with my Meade ETX telescope?

    Yes. This adapter is specifically designed to thread onto the rear cell of Meade ETX models (like the ETX-90/105/125), Celestron C90 spotting scopes, and NexStar 4SE telescopes, allowing you to use any standard 2" eyepiece or accessory.

    How does this Baader adapter improve astrophotography with a NexStar 4SE?

    It provides a single, rigid connection point for your camera, eliminating the flexure and potential image tilt caused by stacking multiple smaller adapters. A solid connection is critical for sharp, round stars, especially during longer exposures.

    Does the Baader 2" Adapter cause vignetting with my camera?

    This adapter provides the largest possible clear aperture from the telescope's rear port. However, Maksutov-Cassegrain telescopes like the C90 and ETX have internal baffles that may still cause some vignetting (darkening of the corners) on cameras with very large sensors, such as full-frame DSLRs. This is a limitation of the telescope's optical design, not the adapter itself.

    What do I need to attach this Baader adapter to my telescope?

    No extra parts are needed. The adapter is designed to unthread your telescope's original 1.25" visual back and thread directly onto the male threads on the rear cell of the optical tube.

    Is this adapter better than using a standard SCT to 2" adapter?

    Yes, because the Celestron C90, NexStar 4, and Meade ETX telescopes do not use the standard Schmidt-Cassegrain (SCT) thread. They have a smaller, proprietary rear port thread. This Baader adapter is purpose-built to match that specific thread, making it the correct and only direct way to adapt these scopes to the 2" format.

  • Net weight (kg) 0.08
    Compatible Brands Astro T-2, Baader Planetarium, Celestron
    Inner Diameter / Clear Aperture (mm) 28
    Outer Diameter 56
    Type of Adapter Filter holder, Reducing Adapter
    Optical length (mm) 9-24
    Inner Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2)
    Outer Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2), 2"/SCT Thread (50.8mm)
    Inner Connection (lens sided) M28.5, 1.4" Thread (35.5 mm), M42 x 0.75 (T-2), 2"/SCT Thread (50.8mm)
  • Baader Planetarium Warranty