William Optics Ultra Flat 132 (0.79x Reducer)

0.79x Reduction: Transform Your FLT132 into an f/5.45 Astrograph

By applying a 0.79x reduction factor, this flattener-reducer converts the FLT132's native f/6.9 focal ratio to a significantly faster f/5.45. This speed increase allows you to capture the same amount of signal in nearly half the time, dramatically improving efficiency during short imaging nights. The corresponding wider field of view lets you frame large celestial targets, such as the Andromeda Galaxy (M31) or the Veil Nebula complex, in a single shot.

3-Element, 3-Group Design: A Flat Field for Full-Frame Sensors

Engineered to correct for field curvature, this unit ensures your images have pinpoint stars from the center to the corners of the sensor. The 3-element, 3-group optical formula is optimized to provide a corrected image circle large enough for full-frame cameras, as well as smaller APS-C and M4/3 formats. This eliminates the frustration of elongated stars at the edge of the field, a critical requirement for producing high-quality astrophotographs.

M92 & M54 Threads: 137.5mm of Precisely Corrected Optical Path

The Ultra Flat 132 ensures a secure, perfectly aligned connection to your imaging train. It attaches directly to the FLT132 focuser via a male M92 x 1 thread, preventing tilt or sag. The camera side features a standard M54 x 0.75 female thread, providing a solid interface for filter wheels, off-axis guiders, and cameras. For optimal optical correction, the total distance from the reducer's M54 shoulder to the camera sensor must be precisely set, accounting for the unit's 137.5 mm optical length.

Native f/6.9 vs. Reduced f/5.45: Choosing the Right Focal Length

Deciding whether to image with the Ultra Flat 132 reducer depends entirely on your target. While the reducer offers significant advantages in speed and field of view, the native focal length of the telescope retains its own utility.

• Native f/6.9 Imaging: The telescope's native focal length provides higher magnification and resolution. This is ideal for smaller targets like the Whirlpool Galaxy (M51), the Ring Nebula (M57), or planetary details where image scale is more important than field of view.
• Reduced f/5.45 Imaging: The 0.79x reducer provides a wider field and cuts exposure times nearly in half. This is the clear choice for large emission nebulae like the North American Nebula (NGC 7000) or for creating mosaics of the Milky Way's core.