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IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2
Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2
Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2
Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2
Baader Polaris I – Measuring and Guiding-25mm Illuminated Eyepiece - T-2

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

by Baader Planetarium
SKU BAA-2954325
$166.00 - $166.00
$166.00
$166.00 - $166.00
$166.00
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  • 25mm Focal Length
  • Illuminated Measuring and Guiding Reticle
  • Direct T-2 Thread Connection
  • Specialized for Manual Guiding
  • Ideal for Precise Polar Alignment
2 in stock
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  • Baader Polaris I – 25mm Illuminated Measuring and Guiding Eyepiece - T-2

    The Baader Polaris I combines a versatile 25mm focal length with an illuminated reticle and a native T-2 thread connection, creating a specialized instrument for precise manual guiding, drift alignment, and celestial measurement.

    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.

  • What is the advantage of the Baader Polaris I's T-2 thread?

    The T-2 thread provides a direct, rigid connection to your focuser or off-axis guider. Unlike a standard 1.25" barrel that can tilt or sag when a set screw is tightened, the threaded connection ensures the eyepiece is perfectly square to the optical axis, eliminating a common source of tracking error from mechanical flexure.

    How does the 25mm focal length of the Baader Polaris I help with manual guiding?

    The 25mm focal length strikes a critical balance. It offers a relatively wide field of view, which makes it much easier to find and center a suitable guide star near your imaging target. At the same time, it provides enough magnification to clearly see small drifts, allowing you to make precise manual corrections.

    Is the illumination on the Baader Polaris I adjustable?

    Yes, illuminated reticle eyepieces like the Baader Polaris I are designed with adjustable brightness. This is essential for matching the reticle's visibility to the brightness of your guide star and sky conditions, ensuring you can see the crosshairs clearly without washing out faint stars.

    Can I use the Baader Polaris I for drift alignment on Polaris with my 8" SCT?

    Absolutely. The Baader Polaris I is an excellent tool for drift alignment. In an 8" f/10 SCT, the 25mm focal length yields about 80x magnification, which is more than enough to detect the subtle drift of a star near the celestial equator. The illuminated reticle makes it easy to track the star's movement precisely against the crosshairs.

    What kind of measurements can I make with the Baader Polaris I eyepiece?

    A measuring eyepiece like the Baader Polaris I, once calibrated for your specific telescope, allows you to measure the angular separation between double stars, determine the position angle of binary systems, and estimate the apparent size of planets or lunar features.

    How would the Baader Polaris I perform in an off-axis guider on a fast f/5 Newtonian?

    The Baader Polaris I is well-suited for an off-axis guider (OAG). Its T-2 thread ensures a solid connection, preventing flexure. The 25mm focal length helps to find guide stars in the limited field of view of an OAG's pick-off prism, which can be challenging, especially with fast Newtonians where guide stars can be comatic.

  • Focal Length 25mm
    Reticle Illuminated, for Measuring & Guiding
    Connection T-2 Thread
    Net weight (kg) 0.14
    Apparent Field of View 40°
    Eye Relief (mm) 15.5 mm
    Field Stop Diameter 18 mm
    Number of Lens Elements 3
    AR-Coating Phantom Coating® Group
    Speciality Cross Aim
    Threaded for filters Yes
    Outer Diameter 36 mm without illumination housing
    Inner Connection (lens sided) M42 x 0.75 (T-2)

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  • Baader Planetarium Warranty