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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 Adapter from M81 to M68 with Stop Ring for ESATTO 3"

PrimaLuceLab Adapter from M81 to M68 with Stop Ring for ESATTO 3"

by PrimaLuceLab
SKU PLL-PL3600262
$95.00 - $95.00
$95.00
$95.00 - $95.00
$95.00
Price Match Policy!
  • Connects M68x1 threaded accessories to M81x1 threaded focusers
  • Designed for the PrimaLuceLab ESATTO 3" and ARCO 3" systems
  • Adds a minimal 4mm of optical path length
  • Includes a 2.5mm stop ring for precise camera rotation and framing
  • Machined aluminum construction with black anodizing
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • PrimaLuceLab Adapter from M81 to M68 with Stop Ring for ESATTO 3"

    The PrimaLuceLab Adapter seamlessly connects your camera or accessories with an M68 female thread to the M81 draw tube of an ESATTO 3" or ARCO 3" unit. This adapter assembly adds only 4mm of total optical length, consisting of the 1.5mm adapter body and a separate 2.5mm stop ring. This ultra-thin profile is critical for preserving precious back focus in complex imaging trains, while the stop ring provides precise rotational control for perfect sensor alignment.

    M81 to M68 Connection: A Minimal 4mm Optical Path

    This adapter provides the essential mechanical link between the large M81 thread on PrimaLuceLab's 3-inch focusers and the common M68x1 thread standard found on many full-frame cameras, filter wheels, and off-axis guiders. By consuming just 4mm of back focus, it allows you to integrate your M68-threaded equipment without compromising your ability to reach focus with reducers or other corrective optics in the imaging train.

    Rotational Framing: Lock Your Camera Angle with the 2.5mm Stop Ring

    The included 2.5mm stop ring is the key to achieving perfect composition. After threading the main 1.5mm adapter onto your focuser, you can back it off slightly to orient your camera sensor to the exact angle you need. You then thread the stop ring up against the adapter to lock it securely in place, ensuring your target is framed exactly as intended without any flexure or rotation during an imaging session.

  • What is the primary use for the PrimaLuceLab M81 to M68 adapter?

    This adapter is designed specifically to connect astrophotography accessories that use a female M68x1 thread to the male M81x1 thread on the draw tube of a PrimaLuceLab ESATTO 3" robotic focuser or ARCO 3" rotator.

    How does the stop ring on this adapter help with astrophotography?

    The stop ring allows you to precisely set the rotational angle of your camera. You can thread the adapter on, adjust the camera's orientation for the best framing of your target, and then tighten the stop ring against the adapter to lock that position securely. This is crucial for composing images of large targets like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000).

    What is the total optical path added by the PrimaLuceLab M81 to M68 adapter?

    The entire assembly adds a total of 4mm to your optical path. This is composed of the 1.5mm thick adapter itself and the 2.5mm thick stop ring. This minimal length helps preserve back focus, which is often limited in astrophotography setups.

    Will this adapter work with focusers other than the ESATTO 3"?

    While it is designed for the ESATTO 3" and ARCO 3", it may work with other focusers that have a male M81x1 thread on the draw tube. However, you must verify the thread specification of your focuser to ensure compatibility.

    I have a camera with an M68 thread. How do I connect it to my ESATTO 3" focuser?

    This adapter is the correct component. You simply thread the M81 side of the adapter onto the ESATTO 3" draw tube, and then thread your M68-equipped camera or accessory onto the other side of the adapter.

    Can I use this adapter to perfectly frame the Rosette Nebula (NGC 2244) with my rectangular camera sensor?

    Yes, this is exactly what the stop ring is for. You can loosen the adapter, rotate your camera to align the long axis of your sensor with the most interesting dimension of the nebula, and then use the stop ring to lock that orientation in place for your imaging run.

  • Adapter Type M81 to M68 Adapter with Stop Ring
    Focuser Side Thread M81x1 Male
    Accessory Side Thread M68x1 Female
    Total Optical Length 4mm
    Adapter Body Thickness 1.5mm
    Stop Ring Thickness 2.5mm
    Compatibility PrimaLuceLab ESATTO 3", ARCO 3"
  • PrimaLuceLab 1-Year Warranty