Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2

The 25mm Focal Length: A Balance for Guiding and Finding

The 25mm focal length provides a moderate magnification that is ideal for manual guiding. It's low enough to offer a wide field of view, making it easier to locate and center suitable guide stars, yet provides enough image scale to detect small deviations in tracking for immediate correction.

Illuminated Reticle: High-Contrast Aiming on Faint Stars

This eyepiece features an illuminated reticle, which is critical for use against a dark sky. The illumination makes the crosshairs clearly visible without overwhelming your dark-adapted vision or washing out faint guide stars, a common problem with non-illuminated crosshair eyepieces.

T-2 System Integration: A Flexure-Free Connection

Unlike standard eyepieces that rely on a slip-fit barrel, the Polaris I uses Baader's T-2 thread system. This provides a direct, rigid connection to your off-axis guider, diagonal, or other T-2 accessories, completely eliminating the potential for sag or flexure that can ruin a long exposure.

Baader Polaris I vs. Standard 1.25" Guiding Eyepieces

While a basic 1.25" crosshair eyepiece can work for guiding, the Baader Polaris I offers distinct advantages for serious imagers.

• Connection Rigidity: A standard 1.25" eyepiece uses a slip-fit barrel held by a set screw, a known source of minor tilt and flexure. The Polaris I's T-2 thread creates a solid, bolted connection that maintains perfect alignment throughout an imaging session.
• Reticle Visibility: Non-illuminated reticles are often black, making them nearly invisible against a dark sky background. The Polaris I's adjustable illumination ensures the reticle is always visible without compromising your ability to see the guide star.
• System Modularity: The T-2 thread makes the Polaris I a native component of the extensive Baader Astro T-2 System, allowing for secure, repeatable integration with a vast range of adapters, extension tubes, and accessories.