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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.
Starlight Instruments 3.0" End Cap for William Optics Male Threaded Accessories
Starlight Instruments 3.0" End Cap for William Optics Male Threaded Accessories

Starlight Instruments 3.0" End Cap for William Optics Male Threaded Accessories

by Starlight Instruments
SKU SI-EC30-1905-92
$150.00 - $150.00
$150.00
$150.00 - $150.00
$150.00
Price Match Policy!
  • Adapts 3.0" Feather Touch focusers to William Optics accessories
  • Provides a male M92x1 threaded connection
  • Eliminates tilt and flexure from compression fittings
  • Ensures a rigid imaging train for astrophotography
  • Machined from high-grade aluminum
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  • Description
  • FAQ
  • Warranty

  • Starlight Instruments 3.0" End Cap for William Optics Male Threaded Accessories

    The Starlight Instruments 3.0" End Cap provides a direct, secure M92x1 threaded connection, replacing the standard compression ring on a Feather Touch focuser to create a rigid, flex-free imaging train with William Optics correctors.

    A Secure M92x1 Threaded Connection for William Optics Correctors

    For astrophotography, a rigid optical train is non-negotiable. This end cap replaces the standard compression ring on any Starlight Instruments 3.0" focuser, offering a solid M92x1 male thread instead. This direct threaded connection eliminates the potential for tilt or sag that can occur with thumbscrew-based adapters, especially when supporting a heavy camera and filter wheel.

    By threading your William Optics field flattener or reducer directly to the focuser drawtube, you ensure perfect alignment and mechanical stability through long exposures and meridian flips. This is the definitive solution for imagers seeking to optimize their field correction and maintain round stars from edge to edge.

  • What is the purpose of the Starlight Instruments 3.0" End Cap with M92x1 threads?

    This end cap is designed for astrophotographers who need to connect a William Optics field flattener or reducer with an M92x1 female thread directly to a Starlight Instruments 3.0" Feather Touch focuser. It creates a secure, threaded connection that prevents tilt and flexure in the imaging train.

    Which focusers is this M92x1 end cap compatible with?

    This end cap is compatible with Starlight Instruments' 3.0" Feather Touch focusers, including both rack and pinion and Crayford models. It is not designed for 2.0", 2.5", or 3.5" focuser models.

    Why use this threaded end cap instead of the standard 2" compression ring on my Feather Touch focuser?

    While a compression ring is adequate for visual use, it can introduce minute amounts of tilt with heavy imaging loads. A threaded connection offers superior rigidity and alignment.

    • Eliminates Tilt: Ensures the camera sensor remains perfectly orthogonal to the optical axis.
    • Prevents Flexure: Supports heavy cameras, filter wheels, and off-axis guiders without sagging.
    • Secure Attachment: Cannot slip or rotate accidentally during an imaging session.

    Will this Starlight Instruments end cap work with my William Optics GT81 or RedCat telescope?

    This adapter is for the focuser side of the connection. It is designed to be installed on a Starlight Instruments 3.0" focuser. It will connect to any William Optics accessory, such as a field flattener, that presents a female M92x1 thread for attachment.

    Does this M92x1 end cap allow for collimation or tilt adjustment?

    No. This is a fixed, solid adapter designed to provide a rigid, non-adjustable connection. Unlike some other Starlight Instruments end caps, it does not feature the three-point collimation set screws. Its purpose is to lock in a precise, square alignment between the focuser and the corrector.

    How do I install the Starlight Instruments 3.0" End Cap?

    Installation is straightforward. You simply unthread the existing end cap (typically a 2" compression ring adapter) from the drawtube of your Starlight Instruments 3.0" focuser and thread the new M92x1 end cap in its place until it is firmly seated.

  • Starlight Instruments 2-Year Warranty