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SVBONY SV161 1.25-inch Double Helical Micro Focuser
SVBONY SV161 Double Helical Micro Focuser - 1.25"
SVBONY SV161 Double Helical Micro Focuser - 1.25"
SVBONY SV161 Double Helical Micro Focuser - 1.25"
SVBONY SV161 1.25-inch Double Helical Micro Focuser

SVBONY SV161 Double Helical Micro Focuser - 1.25"

by SVBONY
SKU SV-F9173B
CA$40.00 - CA$40.00
CA$40.00
CA$40.00 - CA$40.00
CA$40.00
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  • Precise 0.05mm adjustment accuracy for fine focusing
  • 10mm of draw tube travel
  • Non-rotating mechanism keeps camera orientation fixed
  • Standard M42x0.75 T2-threads for universal compatibility
  • Accepts 1.25" eyepieces and accessories
  • Lightweight at only 100g
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • SVBONY SV161 1.25-inch Double Helical Micro Focuser

    The SVBONY SV161 1.25-inch Double Helical Micro Focuser provides critical focus control with a 0.05mm adjustment accuracy over 10mm of travel. Its dual M42x0.75 threads ensure broad compatibility with guide scopes and cameras, while the entire assembly adds only 100g to your imaging train and extends from a minimum height of 43mm to a maximum of 53mm.

    0.05mm Adjustment Accuracy: Fine-Tune Your Guide Star Focus

    Achieving tight, round stars in a long-exposure image depends on precise guiding, which starts with a perfectly focused guide camera. The SV161 helical focuser offers a 0.05mm adjustment accuracy, allowing you to make minute changes that bring faint guide stars into sharp relief. This level of control eliminates the slop and backlash common in basic guide scope focusers, ensuring your autoguiding software has a crisp, high-signal star to lock onto.

    Non-Rotating Stability Across 10mm of Travel

    A common frustration with simple helical focusers is the rotation of the attached camera or eyepiece during adjustment. The SV161's double helical design provides 10mm of smooth focus travel without rotating your camera. This is essential for maintaining your guide star selection in software and keeping your camera's orientation fixed, simplifying setup and calibration. Once focus is achieved, a locking screw holds the position firmly, preventing any drift during an imaging session.

    Universal M42x0.75 Threading and 1.25" Compatibility

    Engineered for versatility, the SV161 features a female M42x0.75 (T2) thread on the telescope side and a male M42x0.75 thread on the camera side. This industry-standard threading allows it to integrate seamlessly into most guide scope and small camera setups without extra adapters. The focuser's 1.25" inner diameter also allows you to use it visually with 1.25" eyepieces, making it a useful tool for accurately setting the focus of a finder or guide scope before attaching a camera.

  • What is the advantage of the SVBONY SV161 over a guide scope's built-in focuser?

    The SVBONY SV161 provides significantly finer control with its 0.05mm adjustment accuracy. Most built-in focusers on guide scopes are simple sliding tubes or have coarse threads, making precise focus difficult. The SV161's double helical mechanism eliminates this issue, allowing for the critical sharpness needed for accurate autoguiding.

    Will the SVBONY SV161 rotate my guide camera when I adjust focus?

    No, it will not. The SV161 uses a non-rotating double helical design. This means your camera or eyepiece remains in a fixed orientation as you move through the 10mm of focus travel, which is critical for maintaining your guide star selection within your software.

    How do I attach the SVBONY SV161 to my equipment?

    The SV161 uses standard M42x0.75 T2-threads. The bottom female thread attaches to your guide scope or off-axis guider, and the top male thread connects to your T-threaded guide camera or a 1.25" eyepiece holder. The 1.25" inner diameter also allows direct insertion of 1.25" nosepieces.

    Is the 10mm travel of the SVBONY SV161 enough for most guide cameras?

    For most setups where the SV161 is used for fine-tuning, the 10mm of travel is sufficient. It is designed to provide precise final adjustments after coarse focus is set by sliding the camera in its holder. For setups requiring a very large focus shift, you may need additional extension tubes.

    Can I use the SVBONY SV161 to get a sharp focus on a guide star near the Pinwheel Galaxy (M101) with my 50mm guide scope?

    Yes. This is an ideal use case. Finding a suitable guide star near a dim target like M101 often means using a fainter star. The SV161's 0.05mm adjustment accuracy will allow you to dial in the focus perfectly, maximizing the signal-to-noise ratio on that faint star and enabling more accurate guiding for your main exposure.

    Will the SVBONY SV161 work with my off-axis guider (OAG)?

    Yes, the SV161 is an excellent tool for focusing an OAG. The limited and often tricky focusing mechanisms on OAGs can be replaced or supplemented by the SV161. Its M42x0.75 threads and non-rotating design make it easy to achieve and lock critical focus on the guide prism without disturbing the main camera.

  • Brand SVBONY
    Inner Diameter 1.25"
    Draw Tube Travel 10mm
    Adjustment Accuracy 0.05mm
    Top Male Thread M42x0.75
    Bottom Female Thread M42x0.75
    Minimum Height 43mm
    Maximum Height 53mm
    Net Weight 100g / 3.53oz

    • 1.25" Double Helical Focuser w/ Female T2-Thread

      × 1

    • M3 Screw

      × 3

  • SVBONY 1-Year Warranty