Sky-Watcher 0.85x Reducer / Flattener for Evostar 120ED

The Sky-Watcher 0.85x Reducer / Flattener for Evostar 120ED is a specialized optical accessory designed to significantly enhance the astrophotography capabilities of the Evostar telescope. By reducing the native focal ratio from f/7.5 to f/6.375, it effectively expands the field of view and decreases required exposure times, allowing you to capture faint celestial details more efficiently. Beyond its role as a reducer, it functions as a high-quality field flattener that eliminates elongated stars at the edges of the frame, ensuring sharp, pinpoint star images across the entire sensor.

This precision-engineered component is designed for seamless integration and ease of use in the field. It features a standard male M48 thread, which allows it to be screwed directly onto the focuser of the Evostar for a secure and stable connection. By combining focal reduction and field flattening into a single unit, this accessory is an essential tool for any astrophotographer looking to achieve professional-grade wide-field images with corrected edge-to-edge clarity.

Product Features in Detail

Optimized Fast Imaging

By dropping the focal ratio to f/6.375, this reducer allows you to collect the same amount of light in less time. This is a game-changer for astrophotographers working with limited clear-sky windows or those looking to capture more targets in a single night.

Professional-Grade Edge Correction

Refractors naturally suffer from "field curvature," where stars near the edge appear as streaks or "seagulls." This flattener creates a flat imaging plane, ensuring that your stars remain sharp points from the center of the frame to the very corners.

Seamless M48 Integration

The use of a male M48 thread on the camera side provides a larger aperture for light to pass through. This is specifically designed to reduce vignetting when using modern large-sensor CMOS and DSLR cameras, providing a more even illumination across the image.

Dedicated System Matching

Unlike "universal" reducers, this unit is engineered specifically for the Evostar's doublet objective. This ensures that the optical corrections are perfectly tuned to the specific focal length and glass characteristics of that telescope.

Rock-Solid Connection

The reducer screws directly into the focuser rather than using a standard push-fit adapter. This screw-on design eliminates "sensor tilt" (where one side of the image is out of focus) caused by the weight of a heavy camera pulling on the drawtube.

Expanded Wide-Field Capability

By reducing the focal length, you can fit larger deep-sky objects into your frame. It is the perfect upgrade for imaging the North American Nebula, the Pleiades, or the Andromeda Galaxy, which might otherwise be too large for the evostar's native focal length.