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Starlight Instruments 3.5" End Cap w/ M48X.75 Threads

by Starlight Instruments
SKU SI-EC35-505-14
CA$266.00 - CA$266.00
CA$266.00
CA$266.00 - CA$266.00
CA$266.00
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  • Attaches to 3.5" Feather Touch focusers
  • Provides a male M48x0.75 threaded connection
  • Creates a rigid, zero-flexure imaging train
  • Ideal for heavy cameras, field flatteners, and filter wheels
  • Eliminates potential for component tilt
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Starlight Instruments 3.5" End Cap w/ M48X.75 Threads

    The Starlight Instruments 3.5" End Cap provides a direct male M48x0.75 threaded connection for all 3.5" Feather Touch focusers. This component replaces the standard compression ring adapter, creating a rigid, flexure-free attachment point essential for heavy imaging trains that utilize the common M48x0.75 filter thread standard.

    A Secure M48x0.75 Interface for Your 3.5" Feather Touch Focuser

    For serious astrophotography, a threaded connection is non-negotiable. This M48x0.75 end cap ensures your entire imaging train—from field flattener and filters to a heavy CCD camera like the FLI Proline 16803—is securely fastened to the focuser drawtube. The direct threading maintains perfect optical alignment by eliminating any possibility of sag or tilt that can occur with thumbscrew-based adapters.

    M48 Threaded Connection vs. 2" Compression Ring: Why It Matters for Imaging

    While a standard 2" compression ring offers convenience for swapping visual eyepieces, it introduces a mechanical weak point for imaging. A threaded connection provides absolute rigidity, ensuring that the camera sensor remains perfectly orthogonal to the optical axis throughout a long exposure, regardless of the telescope's orientation. This prevents elongated stars in the corners of your frames, a common artifact of component tilt in an imaging train secured by compression rings or set screws.

  • What is the primary purpose of the Starlight Instruments 3.5" M48 End Cap?

    Its primary purpose is to provide a solid, threaded M48x0.75 connection point on a 3.5" Feather Touch focuser. This is essential for astrophotography to eliminate flexure and tilt that can occur with standard compression ring adapters, especially when using heavy cameras or accessories.

    How does this M48 End Cap for the 3.5" Feather Touch prevent image tilt?

    By threading directly onto your camera, field flattener, or other M48-threaded accessory, the Starlight Instruments End Cap creates a single, rigid unit with the focuser drawtube. Unlike a compression ring which holds an accessory with friction and thumbscrews, this direct metal-on-metal threaded connection leaves no room for movement or sagging, ensuring perfect alignment.

    Will this Starlight Instruments End Cap fit focusers other than the 3.5" Feather Touch?

    No, this end cap is specifically designed to fit the drawtube of Starlight Instruments 3.5" Feather Touch focusers. It is not compatible with other sizes or brands of focusers.

    How do I attach my 2" light pollution filter using the Starlight Instruments M48 End Cap?

    The M48x0.75 thread on this end cap is the same standard used for 2" filters. You can typically thread your 2" filter directly into an M48-threaded camera nosepiece or filter drawer that you would then attach to this end cap. This ensures the filter is securely held within the rigid imaging train.

    I'm imaging with an FLI Proline 16803 camera on my 3.5" Feather Touch focuser; is this the right part?

    Yes, this is an ideal component for that setup. The FLI Proline 16803 is a substantial camera, and using this M48x0.75 threaded end cap will provide the secure, tilt-free connection required to get the best performance from your 3.5" Feather Touch focuser and camera.

    When should I choose this M48 threaded end cap over the standard 2" compression ring on my Feather Touch focuser?

    You should choose the M48 threaded end cap for any astrophotography application. The standard 2" compression ring is sufficient and more convenient for visual observing where small amounts of tilt are unnoticeable. For imaging, the rigidity of a threaded connection is critical for sharp, round stars across the entire frame.

  • Compatibility Starlight Instruments 3.5" Feather Touch Focusers
    Thread Type M48x0.75 Male

    • 3.5" End Cap w/ M48X.75 Threads

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  • Starlight Instruments 2-Year Warranty