William Optics FLAT 61A Field Flattener

The William Optics FLAT 61A is a 1.0x field flattener designed to improve edge-to-edge star sharpness when imaging with compatible William Optics refractors, especially the Zenithstar 61. It helps correct field curvature so astrophotographers can capture cleaner stars across APS-C and full-frame camera sensors.

Who Is This Product Best For?

The FLAT 61A is best for astrophotographers using a Zenithstar 61 or compatible small William Optics refractor who want a flatter imaging field for deep-sky photography.

Why Choose This Product?

• 1.0x correction: Flattens the field without reducing focal length.
• APS-C and full-frame support: Designed for common astronomy and DSLR/mirrorless camera setups.
• Camera adapter support: Uses an M48 camera-side thread and supports common T-mount ecosystems.

Recommended Uses

• Wide-field deep-sky astrophotography
• Improving star shape at the edge of the frame
• Zenithstar 61 imaging setups

Compatibility and Accessory Notes

Use the recommended back focus spacing for your telescope and camera. Customers should confirm camera adapter, T-ring, and spacing requirements before imaging.

Important Limitations

This is an imaging accessory, not a visual observing accessory. Correct spacing is required for best results.

Frequently Asked Questions

Does the FLAT 61A reduce focal length?

No. It is a 1.0x field flattener.

Which telescope is it mainly for?

It is primarily intended for Zenithstar 61 imaging systems.

Our Recommendation

Choose the FLAT 61A if you image with a Zenithstar 61 and want cleaner corner stars without changing the telescope’s focal length.