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William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8
William Optics WO x0.72 Reducer Flattener 8

William Optics WO x0.72 Reducer Flattener 8

by William Optics
SKU WO-P-FLAT8
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$806.00
$806.00 - $806.00
$806.00
$765.70
$765.70 - $765.70
$765.70
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  • Reduces focal ratio by a factor of 0.72x
  • Corrects field curvature for full-frame sensors
  • 3-element, 3-group optical design
  • Connects to telescope via M92 x 1 thread
  • Standard M48 x 0.75 camera-side threading
  • Weighs 1098 g (2.42 lbs)
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • William Optics WO x0.72 Reducer Flattener 8

    The William Optics WO x0.72 Reducer Flattener 8 is engineered to transform high-focal-length William Optics refractors into faster, wide-field astrographs capable of illuminating full-frame sensors. Its 3-element, 3-group design provides a 0.72x focal reduction, significantly decreasing exposure times while correcting for field curvature from edge to edge. This unit connects to the telescope focuser via a robust M92 x 1 thread and provides a standard M48 x 0.75 thread for direct attachment to modern DSLR and dedicated astronomy cameras.

    A Faster, Wider Field: 0.72x Reduction for Large Refractors

    The primary function of the Flattener 8 is to reduce your telescope's effective focal length by a factor of 0.72x. For an f/7 refractor, this transforms the optical system into a faster f/5.04 instrument, cutting required exposure times by nearly 50%. This speed advantage allows you to capture more data on faint targets in a single night and increases the field of view to frame large objects like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000).

    Edge-to-Edge Correction: Full-Frame Illumination with a 3-Element Design

    Designed specifically for large-aperture refractors, the Flattener 8 provides a corrected image circle that fully supports full-frame (36x24mm) camera sensors. The 3-element optical system in 3 groups is optimized to eliminate field curvature and minimize off-axis aberrations, ensuring that stars remain tight, pinpoint sources across the entire frame. This avoids the bloated, comatic stars in the corners that are common in uncorrected systems, delivering professional-grade astrophotography results.

    Robust Integration: M92 Telescope Thread and M48 Camera Support

    The Flattener 8 is built for a secure, flex-free imaging train. It attaches to compatible William Optics focusers using a large M92 x 1 male thread for a rigid connection. On the camera side, it terminates in a standard M48 x 0.75 male thread, the ideal interface for connecting filter wheels, off-axis guiders, and a wide range of camera-specific T-rings. At 1098 g (2.42 lbs), its solid construction ensures optical alignment is maintained, though it requires a robust focuser to handle the load.

  • Which William Optics telescopes are compatible with the Flattener 8?

    The Flattener 8 is designed for William Optics' larger refractors that feature a focuser with a female M92 x 1 thread. It is made for the Fluorostar 132 (FLT132), Fluorostar 156 (FLT156), Gran Turismo 102 (GT102) and Gran Turismo 153 (GT153). Always confirm your telescope's focuser thread before purchasing.

    Does the WO Flattener 8 provide a fully corrected field for a full-frame sensor?

    Yes, it is explicitly designed to provide excellent correction and illumination for full-frame sensors (36x24mm), as well as smaller APS-C and M4/3 formats. You can expect sharp, pinpoint stars from the center to the corners of your full-frame camera.

    How does the 0.72x reduction of the Flattener 8 affect my imaging time?

    Focal reduction makes your telescope "faster" by concentrating the same amount of light onto a smaller area. A 0.72x reducer shortens exposure times by a factor of (0.72)^2, or approximately 0.52. This means a 10-minute exposure without the reducer would require only about 5 minutes to achieve the same signal-to-noise ratio with the Flattener 8 installed.

    What is the required back focus for the William Optics Flattener 8?

    While the optical length is 77 mm, the required back focus (the distance from the flattener's rear flange to the camera sensor) depends on the telescope: 63.4 mm for the FLT132, 60.8 mm for the FLT156, 67.1 mm for the GT102 and 60.4 mm for the GT153, with adjust distances of 8.4 mm, 5.8 mm, 12.1 mm and 5.4 mm respectively.

    What are the connection threads on the WO Flattener 8?

    The Flattener 8 uses two primary threads:

    • Telescope Side: M92 x 1 male thread.
    • Camera Side: M48 x 0.75 male thread (also known as the 2" filter thread standard).

    Is the 1098 g weight of the Flattener 8 a concern for my telescope's focuser?

    At 2.42 lbs, the Flattener 8 is a substantial piece of optical equipment. It requires a high-quality, robust focuser capable of handling heavy imaging trains without slipping or flexing. The rack-and-pinion focusers found on the William Optics telescopes it's designed for are more than capable of supporting this weight along with a camera.

  • Reducer Power 0.72x
    Optical Design 3 Elements in 3 Groups
    Camera Format Support Full Frame, APS-C, M4/3
    Telescope Connection M92 x 1 x 7.5 mm Thread
    Camera Connection M48 x 0.75 x 4 mm Thread
    Supported T-Mounts Canon EF, RF; Nikon F, Z; Sony E; Pentax K; MFT (M4/3); FUJI X
    Optical Length 77 mm
    Weight 1098 g / 2.42 lbs
    Required back focus 63.4 mm (FLT132), 60.8 mm (FLT156), 67.1 mm (GT102), 60.4 mm (GT153)
    Image circle 44.4 mm
    Designed for FLT132, FLT156, GT102, GT153
    Magnification Factor 0.72x

    • William Optics WO x0.72 Reducer Flattener 8

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  • William Optics 2-Year Warranty