Skip to content
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.
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.
Celestron Reducer - Corrector
Celestron Reducer - Corrector

Celestron Reducer - Corrector

by Celestron
SKU CEL-94175
$199.95 - $199.95
$199.95
$199.95 - $199.95
$199.95
Price Match Policy!
  • Reduces telescope focal length by 37%
  • Converts f/10 SCTs to f/6.3 and f/11 systems to f/7
  • Compatible with Celestron C5, C6, C8, C9.25, C11, and C14 SCTs
  • Fully multi-coated optics for maximum light transmission
  • Weighs just 4.3 oz (121.90 g)
Backordered
Request Stock Alert
Availability Info
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Celestron f/6.3 Reducer - Corrector

    The Celestron Reducer - Corrector transforms your Schmidt-Cassegrain telescope, effectively giving you two instruments in one by reducing the focal length by 37% to convert a native f/10 system into a faster f/6.3 optical train. This 4-element, fully multi-coated lens threads directly onto the rear cell of C5 to C14 SCTs, weighs only 4.3 oz (121.90 g), and measures 56mm in diameter. For astrophotographers, this focal reduction shortens exposure times by more than half, allowing you to capture faint deep-sky objects with greater efficiency.

    Convert f/10 to f/6.3: A 37% Focal Length Reduction

    This corrector-reducer lens alters the primary optical characteristics of your standard SCT. By reducing the focal length by 37%, it changes an f/10 telescope to a much faster f/6.3 system, and an f/11 telescope to f/7. This has profound benefits for both visual observation and imaging.

    Visually, you achieve a wider true field of view with any given eyepiece, making it easier to locate objects and frame large targets like the Andromeda Galaxy (M31) or the Pleiades (M45). For imaging, the faster focal ratio dramatically cuts down on necessary exposure time, allowing you to gather the same amount of signal in about one-third of the time required at f/10.

    For C5 to C14 Standard SCTs: Visual and Photographic Use

    This reducer is designed specifically for Celestron's standard line of Schmidt-Cassegrain telescopes, offering broad compatibility from the portable C5 up to the observatory-class C14. It threads directly onto the rear cell, creating a secure connection for your imaging train or visual back.

    Once installed, you can attach standard accessories like a T-Adapter for your DSLR or a 1.25" visual back for diagonals and eyepieces. While it does provide some field-flattening for improved edge-of-field sharpness, its primary function is focal reduction, making it an essential tool for deep-sky astrophotography with non-EdgeHD optical tubes.

    4.3 oz Machined Aluminum Body with Fully Multi-Coated Optics

    Engineered for durability and optical clarity, the reducer is housed in a precisely machined aluminum body with a black anodized finish, weighing a mere 4.3 oz. The internal surfaces are blackened and glare-threaded to suppress internal reflections and maximize image contrast, ensuring a dark sky background.

    • Fully Multi-coated Lenses: Every air-to-glass surface features high-transmission coatings to ensure maximum light throughput and minimal reflection, preserving the brightness and fidelity of the image.
    • Knurled Grip: A textured, knurled surface provides a secure grip for easy threading and unthreading, even when wearing gloves in cold conditions.
    • Compact Design: At only 34mm (1.34") in length, it adds minimal backfocus to your optical train, preserving compatibility with most existing accessories.

    Standard SCT vs. EdgeHD: Why This Reducer is Not for EdgeHD Optics

    It is critical to note that this f/6.3 reducer is engineered for standard Schmidt-Cassegrain telescopes only and is not compatible with Celestron's EdgeHD optical tubes. EdgeHD telescopes have a built-in flattener and require a dedicated, optically matched reducer (like the Celestron .7x Reducer) to maintain their flat-field, coma-free imaging circle.

    Using this standard reducer on an EdgeHD telescope will result in degraded optical performance and will not achieve the designed image quality of the EdgeHD system. If you own an EdgeHD scope, you must use the reducer specifically designed for that optical system.

  • How does the Celestron f/6.3 Reducer change the view in my 8" f/10 SCT?

    In a Celestron 8" SCT with a native 2032mm focal length, this reducer converts it to approximately 1280mm at f/6.3. With a 25mm eyepiece, your magnification would drop from 81x to 51x, and your field of view would become significantly wider, making it easier to fit large deep-sky objects like the Orion Nebula (M42) into a single frame.

    What is the optimal backfocus for the Celestron Reducer - Corrector?

    The optimal backfocus distance from the rear flange of the reducer to the camera sensor is approximately 105mm. Achieving this distance is crucial for obtaining the best possible image quality and the advertised focal reduction. You may need to use spacer rings to precisely match this distance with your specific camera and accessories.

    Can I use this Reducer - Corrector with an Off-Axis Guider (OAG)?

    Yes, you can use an OAG with this reducer. However, you must ensure that the total light path of your OAG, camera, and any adapters adds up to the required 105mm of backfocus for optimal performance. This often requires careful selection of components to hit the target spacing.

    Why can't I use this reducer on my Celestron EdgeHD 9.25" telescope?

    EdgeHD optical systems are designed with an integrated field flattener to provide a perfectly flat field for imaging. They require a specific, matched 0.7x reducer lens that is designed to work with that flattened field. Using this standard f/6.3 reducer on an EdgeHD will introduce optical aberrations and will not maintain the edge-to-edge sharpness that is the primary feature of the EdgeHD design.

    Does this reducer completely eliminate field curvature in my standard SCT?

    No, it does not completely eliminate it. While the Celestron Reducer - Corrector does diminish some of the inherent field curvature of a standard SCT, its primary purpose is focal length reduction. You will notice flatter fields and sharper stars at the edge compared to using the telescope at its native focal length, but it does not produce a perfectly flat field like an EdgeHD system.

    Is this Celestron Reducer - Corrector compatible with non-Celestron SCTs?

    This reducer is optically designed and optimized for Celestron Schmidt-Cassegrain telescopes. While it may physically thread onto other brands of SCTs that use the standard 2" rear cell thread, optical performance is not guaranteed and may vary.

  • Optical Design Reducer - Corrector
    Lens Coatings Fully Multi-coated
    Focal Reduction 0.63x (37% reduction)
    Body Material Machined aluminum
    Compatibility Celestron C5, C6, C8, C9.25, C11, C14 (Standard SCTs only)
    Incompatible With EdgeHD, Maksutov-Cassegrain, Refractor, Newtonian Telescopes
    Diameter 56mm (2.2")
    Length 34mm (1.34")
    Weight 4.3 oz (121.90 g)
    • Celestron Reducer - Corrector

      Celestron f/6.3 Reducer - Corrector

      × 1

    • Front Dust Cap

      Front Dust Cap

      × 1

    • Rear Dust Cap

      Rear Dust Cap

      × 1

  • Celestron 2-Year Warranty