Askar Focal Plane Adjuster

Spherical Adjustment: Correct Tilt Without Changing Back Focus

Sensor tilt is a primary cause of elongated stars at the edge of an image, especially with large-format cameras. Traditional push-pull adjusters can correct tilt, but the adjustment process itself often changes the distance between the corrector and sensor, disrupting the calculated back focus. The Askar Focal Plane Adjuster solves this with a unique spherical mechanism that pivots the focal plane without changing the optical path length, ensuring your back focus remains constant throughout the adjustment process.

18mm Profile & M54/M48 Threads for Seamless Compatibility

Engineered with a precise 18mm thickness, this adjuster is designed for easy integration into existing imaging trains. For users of specific Sharpstar and Askar telescopes (including the APO series, ASKAR V, 71F, and 50EDPH), the 18mm body directly replaces the standard M48 filter thread ring, requiring no recalculation of back focus. The unit features a female M54 front thread and a male M48 rear thread, and an included M54-to-M48 adapter ring converts the front thread for maximum compatibility with a wide range of correctors and accessories.

Precision Control: ±1° Range with 5' Graduations

Achieving a perfectly flat field requires fine control. The Askar Focal Plane Adjuster offers a ±1° tilt range, which is more than sufficient to correct for common alignment issues in focusers and camera sensors. The adjustment is made by simply rotating the handle, eliminating the need for tools or repeated disassembly of your imaging train. Laser-engraved markings at 5-arcminute intervals allow you to make deliberate, repeatable adjustments to achieve perfect star shapes across your entire frame.

Askar Spherical Adjuster vs. Traditional Push-Pull Designs

While three-point push-pull tilt plates are a common solution, they present a significant trade-off. Their primary disadvantage is that adjusting one screw affects the overall optical distance, forcing you to constantly re-evaluate back focus.

• Push-Pull Adjusters: These require a delicate balance of loosening and tightening opposing screws. This action physically moves the camera mounting plate forward or backward, altering the precise spacing your flattener or reducer requires.
• Askar Spherical Adjuster: This design pivots the entire optical assembly around a central point. The adjustment handle smoothly changes the tilt angle without any change in the front-to-back thickness, preserving your back focus and simplifying the entire process of achieving a perfectly flat imaging plane.