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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.
PrimaLuceLab M81 25mm Extension Tube for ESATTO 3"

PrimaLuceLab M81 25mm Extension Tube for ESATTO 3"

by PrimaLuceLab
SKU PLL-PL3600285
$55.00 - $55.00
$55.00
$55.00 - $55.00
$55.00
Price Match Policy!
  • Adds a fixed 25mm of back focus
  • Threads: M81x1 Male to M81x1 Female
  • Designed specifically for the PrimaLuceLab ESATTO 3" Focuser
  • CNC-machined from a single block of aluminum
  • Black anodized finish to minimize internal reflections
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • PrimaLuceLab M81 25mm Extension Tube for ESATTO 3"

    The PrimaLuceLab M81 25mm Extension Tube adds a fixed 25mm of spacing to the optical train of any ESATTO 3" robotic focuser. It threads directly to the focuser's M81 draw tube, providing the critical distance required to bring cameras and complex imaging trains to a precise focus point when the standard travel is insufficient.

    Rigid 25mm Spacing for ESATTO 3" M81 Systems

    This 25mm extension is an essential component for imagers who need to achieve focus with setups that require more back focus than the ESATTO 3" focuser's native draw tube travel provides. By inserting this rigid spacer, you can easily accommodate off-axis guiders, filter wheels, or cameras with deeply recessed sensors without compromising the stability of your imaging train.

    • Solid Construction: Machined from a single piece of aluminum and black anodized, the extension maintains perfect optical alignment and prevents stray light from reducing contrast.
    • M81 Thread Standard: With male and female M81 threads, it installs seamlessly between the ESATTO 3" draw tube and other M81 adapters, such as reducers or camera rotators.
    • System Integration: As part of the PrimaLuceLab ecosystem, this extension is designed to work flawlessly with all ESATTO 3" camera adapters, ensuring a secure, threaded connection throughout your entire setup.

  • What is the primary purpose of the PrimaLuceLab M81 25mm Extension Tube?

    Its primary purpose is to add a fixed 25mm of length to your optical path. This is necessary when your camera's sensor cannot reach the focal plane using only the ESATTO 3" focuser's draw tube travel, a common issue when using accessories like focal reducers or off-axis guiders.

    How does this 25mm extension tube attach to the ESATTO 3" focuser?

    The extension tube features M81x1 threads on both ends. The male thread screws directly into the M81 female thread on the ESATTO 3" focuser's draw tube, and the female end accepts any other M81-threaded accessory from the PrimaLuceLab line.

    When would I need to use the M81 25mm Extension Tube with my refractor telescope?

    You would use it if, after adding a focal reducer, filter wheel, and camera, you find that you run out of "out-travel" on your ESATTO 3" focuser before the stars become sharp. The 25mm extension effectively pushes your entire imaging train outward, bringing it into the focuser's range.

    Can I stack multiple PrimaLuceLab M81 25mm extension tubes for more length?

    Yes, you can thread multiple extensions together to create longer spacers (e.g., two for 50mm). However, for longer distances, it is often better to use a single, longer extension if available to maximize rigidity and minimize the number of connection points.

    What is the M81 25mm Extension Tube made of?

    It is CNC-machined from a solid block of aluminum for high strength and low weight. It is then black anodized to provide a durable, scratch-resistant finish and to prevent internal reflections that could degrade image contrast.

    Will this M81 25mm extension tube work with focusers other than the ESATTO 3"?

    While it is designed specifically for the PrimaLuceLab ESATTO 3" focuser, it will theoretically work with any focuser or adapter that uses a standard M81x1 thread. However, compatibility and correct spacing for other systems are not guaranteed.

  • Thread Type M81x1 Male and Female
    Extension Length 25mm
    Compatibility PrimaLuceLab ESATTO 3" Focuser
    Material Anodized Aluminum
  • PrimaLuceLab 1-Year Warranty