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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.
ZWO FF65 APO 0.75× Full Frame Reducer

ZWO FF65 APO 0.75× Full Frame Reducer

by ZWO
SKU ZWO-F65RE
$199.00 - $199.00
$199.00
$199.00 - $199.00
$199.00
Price Match Policy!
  • Reduces FF65 APO focal ratio to f/4.8
  • 0.75x reduction factor for wider fields of view
  • Standard 55mm back focus from the M48 thread
  • Integrated M48x0.75 (2-inch) filter thread
  • Quad-element design for full-frame correction
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • ZWO 0.75x Full-Frame Reducer for FF65-APO Refractor

    The ZWO 0.75x Full-Frame Reducer transforms the FF65-APO into a faster f/4.8 imaging system, using a four-element optical design to achieve wider fields of view. This 0.75x reduction factor allows you to capture large targets with significantly shorter exposure times, while the standard 55mm back focus ensures compatibility with your existing full-frame camera and filter setup via the included M48 adapter.

    Achieve a Faster f/4.8 Focal Ratio

    By shortening the native focal ratio of the FF65-APO, this 0.75x reducer gathers light more quickly, effectively reducing total integration time required for faint deep-sky objects. An f/4.8 system is substantially faster than the telescope's original configuration, letting you complete projects in a fraction of the time and maximize data collection on clear nights. This speed is critical for capturing faint nebulosity in targets like the North American Nebula (NGC 7000) or the Heart Nebula (IC 1805).

    Full-Frame Correction with 55mm Back Focus

    Engineered with a quad-element optical layout, the reducer maintains sharp, well-corrected stars across a full-frame sensor. It establishes a standard 55mm back focus distance from the base of its M48 threads, simplifying camera and accessory connection. This industry-standard spacing is designed to accommodate a DSLR with a T-ring, or a dedicated astronomy camera with a filter wheel and off-axis guider, without complex calculations.

    • Standardized Connection: The 55mm spacing allows for direct attachment of most ZWO ASI cameras and filter wheels, creating a rigid, threaded imaging train.
    • Four-Element Design: Corrects for optical aberrations introduced by the reduction process, ensuring stars remain tight and round to the edge of the frame.

    Integrated 2-inch Filter Thread and Adapters

    The reducer includes both M54 and M48 threaded adapters for direct, secure attachment to the FF65-APO focuser and your camera system. A built-in M48x0.75 (2-inch) filter thread is machined into the reducer assembly, allowing you to place light pollution or narrowband filters directly into the optical path. This placement is ideal for minimizing reflections and vignetting, especially with fast f/4.8 optics.

  • What does the ZWO 0.75x Reducer do to the FF65-APO's focal length?

    The ZWO 0.75x Reducer shortens the FF65-APO's native 416mm focal length to approximately 312mm. This creates a much wider field of view, allowing you to frame large celestial objects like the Andromeda Galaxy (M31) or the entire Veil Nebula complex in a single shot with a full-frame sensor.

    How do I connect my camera to the ZWO F65RE Reducer?

    The reducer provides a standard 55mm back focus from its M48x0.75 male threads. You can connect your ZWO camera, filter wheel, and off-axis guider using the appropriate M48 spacers to achieve this 55mm distance. For a DSLR, a standard M48 T-ring will typically provide the correct spacing automatically.

    Can I use 2-inch filters with this ZWO reducer?

    Yes. The reducer has a built-in female M48x0.75 thread on the telescope side, designed to accept standard 2-inch astronomy filters. This allows you to easily add light pollution, L-Pro, or narrowband filters to your imaging train.

    Is this reducer compatible with telescopes other than the ZWO FF65-APO?

    No, this 0.75x reducer is optically matched specifically for the ZWO FF65-APO refractor. Using it with other telescopes will likely result in poor optical correction, field curvature, and stars that are not sharp at the edge of the field.

    Does the ZWO F65RE reducer change the image circle?

    The reducer is designed to provide excellent illumination and correction across a full-frame sensor (44mm image circle) when paired with the FF65-APO. It maintains the telescope's full-frame imaging capability while making the field of view wider.

    How much faster is f/4.8 compared to the FF65's native f/6.4 for imaging the Orion Nebula (M42)?

    An f/4.8 system is approximately 1.78 times faster than an f/6.4 system. This means that for a target like the Orion Nebula (M42), an exposure that would take 180 seconds at f/6.4 would only require about 101 seconds at f/4.8 to achieve the same signal level, allowing you to gather more data in less time.

  • SKU ZWO-F65RE
    Reduction Factor 0.75x
    Resulting Focal Ratio f/4.8 (with FF65-APO)
    Optical Design 4-element
    Back Focus 55mm
    Filter Thread M48x0.75 (2-inch)
    Adapters Included M54 and M48
    Compatibility ZWO FF65-APO Refractor

    • 0.75x Full-Frame Reducer for FF65-APO

      × 1

    • M54 Adapter

      × 1

    • M48 Adapter

      × 1

    • Dust Caps

      × 2

  • ZWO 2-Year Limited Warranty