What does "1.0x power" mean for the William Optics Flat73A?
A 1.0x flattener corrects for field curvature without changing the focal length or f-ratio of your telescope. With the Flat73A, your ZenithStar 73 will operate at its native focal length, producing images with the same scale and field of view as it would without the flattener, but with the benefit of sharp stars across the entire frame.
Can I use the Flat73A flattener with a telescope other than the Z73?
No, the Flat73A is optically and mechanically designed specifically for the William Optics ZenithStar 73. It uses a proprietary M63 x 1 thread to attach to the Z73's focuser and its optical prescription is matched to that telescope's specific objective lens.
What is the maximum sensor size the Flat73A can illuminate and correct?
The William Optics Flat73A is designed to provide a corrected, unvignetted image circle for camera sensors up to full-frame size. It is also perfectly suitable for smaller APS-C and Micro Four Thirds sensors.
How do I connect my Nikon Z mirrorless camera to the Flat73A?
You will need an M48 T-ring specifically made for the Nikon Z-mount. The Flat73A provides the standard M48 x 0.75 male thread that the T-ring will attach to. The adjustable mechanism on the flattener then allows you to set the correct distance to your camera's sensor for optimal correction.
How will the Flat73A improve my images of the North American Nebula (NGC 7000) with a Z73?
The ZenithStar 73 provides a wide field of view perfect for large targets like the North American Nebula (NGC 7000). However, without correction, stars at the edges of such a large object will appear elongated or out of focus. The Flat73A corrects this distortion, ensuring that every star across the vast nebula complex is rendered as a sharp, round point, resulting in a much cleaner and more professional final image.
Is the Flat73A necessary if I'm only using an APS-C camera with my Z73?
Yes, absolutely. While an APS-C sensor is smaller than full-frame, the field curvature of the Z73 is still significant enough to be visible on an APS-C chip. Using the Flat73A will provide a noticeably flatter field, which is critical for accurate guiding, clean image stacking, and producing high-quality images where the corner performance matches the center.
