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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.
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.
William Optics Ultra Flat 156 (0.79x Reducer)
William Optics Ultra Flat 156 (0.79x Reducer)
William Optics Ultra Flat 156 (0.79x Reducer)
William Optics Ultra Flat 156 (0.79x Reducer)

William Optics Ultra Flat 156 (0.79x Reducer)

by William Optics
SKU WO-P-FLAT-156
$1,068.00 - $1,068.00
$1,068.00
$1,068.00 - $1,068.00
$1,068.00
Price Match Policy!
  • Reduces focal ratio by a factor of 0.79x
  • Designed for Medium Format, Full Frame, and APS-C sensors
  • 3-element, 3-group optical design
  • Requires 75.5mm of optical length (back focus)
  • Connects to focusers via an M92 x 1 thread
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Ultra Flat 156 (0.79x Reducer)

    The Ultra Flat 156 reducer shortens your telescope's focal length by a factor of 0.79x, using a 3-element, 3-group optical design to deliver wider fields of view for sensors up to Medium Format. It establishes a precise 75.5mm optical length from its M54 camera-side thread and connects to the focuser via a robust M92 x 1 thread. Weighing 1202 g (2.65 lbs), this reducer is built to support large, modern CMOS and CCD cameras without flexure.

    0.79x Reduction: Faster Imaging and Wider Fields of View

    This reducer transforms your telescope's imaging characteristics by reducing its effective focal length. A 0.79x reduction factor not only expands your field of view to capture larger celestial objects but also accelerates your imaging sessions. By concentrating the same amount of light onto a smaller area, it effectively makes your telescope faster, allowing you to gather more signal in less time.

    3-Element Design: A Flat Field for Medium Format and Larger Sensors

    Engineered with a 3-element optical formula arranged in 3 distinct groups, the Ultra Flat 156 is designed to deliver a flat, well-corrected image plane across very large sensors. It provides full illumination for Medium Format, Full Frame, APS-C, and M4/3 camera formats. This ensures that you can utilize the full potential of modern, large-format astronomy cameras, achieving sharp, pinpoint stars from the center to the corners of your frame.

    Mechanical Integration: M92 Threads and 75.5mm Optical Length

    The Ultra Flat 156 is designed for robust, threaded connections within the imaging train. It features an M92 x 1 male thread for attachment to a compatible focuser and an M54 x 0.75 male thread on the camera side. Achieving critical focus requires a precise optical length of 75.5mm from the reducer's shoulder to the camera sensor. At 2.65 lbs (1202 g), its substantial build demands a high-capacity focuser and careful attention to mount balancing.

  • What is the primary function of the Ultra Flat 156 reducer?

    The Ultra Flat 156 serves two main purposes: it reduces your telescope's focal length by a factor of 0.79x, which provides a wider field of view, and it flattens the image plane to ensure sharp stars across large camera sensors.

    What cameras are compatible with the Ultra Flat 156 reducer?

    This reducer is designed to illuminate a wide range of sensor sizes, including Medium Format, Full Frame, APS-C, and M4/3. It connects to the camera or filter wheel via a standard M54 x 0.75 male thread.

    How do I achieve the correct 75.5mm spacing for the Ultra Flat 156?

    The required 75.5mm optical length, or back focus, is measured from the shoulder of the reducer's M54 thread to your camera's sensor. You will need to use a combination of M54 extension rings and adapters to precisely match this distance for your specific camera setup.

    What kind of telescope focuser does the Ultra Flat 156 connect to?

    The Ultra Flat 156 features an M92 x 1 male thread on the telescope side. It is designed to thread directly into a focuser drawtube with a matching M92 female thread for a secure, tilt-free connection.

    I have a full-frame camera like a ZWO ASI6200MM. Will the Ultra Flat 156 fully illuminate its sensor?

    Yes. The Ultra Flat 156 is specified to cover sensors up to Medium Format, which is larger than the sensor in a full-frame camera. It will provide a flat, well-corrected, and fully illuminated field for your full-frame camera, ensuring no vignetting or distorted stars at the edges.

    Given its 2.65 lbs weight, what should I consider when adding the Ultra Flat 156 to my setup?

    The significant weight of 1202 g (2.65 lbs) requires careful consideration. First, ensure your focuser can handle the load without slipping or tilting. Second, you will need to re-balance your telescope on the mount after installing the reducer and camera to prevent tracking errors and strain on the motors.

  • Flattener Power 0.79 x
    Lens Type 3 Groups 3 Elements
    Camera Format Compatibility Medium Format, Full Frame, APS-C, M4/3
    Optical Length (Back Focus) 75.5 mm
    Telescope Side Thread M92 x 1 x 6.5 mm
    Camera Side Thread M54 x 0.75 x 4 mm
    Weight 1202 g / 2.65 lbs

  • Warranty information for this product is not available.