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SVBONY SV157 1.25-inch Extension Tube (56mm / 70mm)
SVBONY SV157 56mm Extension Tube - 1.25"
SVBONY SV157 56mm Extension Tube - 1.25"
SVBONY SV157 1.25-inch Extension Tube (56mm / 70mm)

SVBONY SV157 56mm Extension Tube - 1.25"

by SVBONY
SKU SV-W9118A
$11.19 USD - $11.19 USD
$11.19 USD
$11.19 USD - $11.19 USD
$11.19 USD
Price Match Policy!
  • Adds a fixed 56mm of length to the optical path
  • Standard 1.25-inch barrel diameter
  • CNC-machined aluminum for rigidity
  • Solves focusing issues with cameras and certain eyepieces
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • SVBONY SV157 1.25-inch Extension Tube (56mm)

    The SVBONY SV157 1.25-inch Extension Tube solves common focusing problems by providing a fixed 56mm of additional length to your optical path. Constructed from CNC-machined aluminum, it ensures a rigid, non-flexing connection for any standard 1.25-inch focuser, diagonal, or accessory, making it an essential tool for both imaging and visual astronomy.

    Achieve Critical Focus: Adding 56mm of Optical Path

    Certain cameras, particularly DSLRs, have sensors that are too recessed to reach focus in telescopes with limited focuser travel. The SV157 extension tube bridges this gap, pushing the focal plane outwards to meet your sensor. It is also essential for using eyepieces that require significant out-travel, especially in reflector telescopes or when using accessories like focal reducers.

    CNC-Machined Construction for a Secure 1.25-inch Fit

    Unlike plastic alternatives, the SV157 is CNC-machined from aluminum for rigidity and durability. This prevents any sag or tilt, even when supporting a heavy eyepiece or camera, which is critical for maintaining sharp, round stars across the field.

  • When would I need the SV157 1.25-inch Extension Tube with my Newtonian reflector and a DSLR camera?

    Many Newtonian reflectors do not have enough "out-travel" on their focusers to bring a DSLR camera's sensor to the focal plane for prime-focus astrophotography. The SVBONY SV157 adds the necessary length to the optical path, allowing you to achieve a sharp, infinity focus that would otherwise be impossible.

    I can't get my short-focal-length eyepiece to focus in my Maksutov-Cassegrain. Will the SV157 extension tube help?

    Yes, it's a common issue. Some eyepieces, especially those with Barlows or other optical groups, require more outward focuser travel than a Maksutov's internal focusing mechanism can provide. The SV157 1.25-inch Extension Tube can provide the extra distance needed to bring these specific eyepieces into a sharp focus.

    Is the 56mm SV157 extension tube the right length for my setup?

    The choice depends entirely on how much extra focus travel you need. It's best to measure the gap by first trying to focus your equipment and estimating the remaining distance. Since the SV157 is a fixed-length tube, check that 56mm matches the distance you need.

    Can I stack multiple SV157 extension tubes?

    Yes, you can stack multiple tubes to achieve longer extensions. However, be mindful that creating a very long, unbraced accessory train can introduce flexure or place excessive leverage on your focuser. For very long extensions, a single, longer tube is often a more stable solution.

    Will the SVBONY SV157 add any optical distortion to my view?

    No. Because the SV157 is a hollow tube with no lenses or glass elements, it does not alter the optical properties of your telescope. It purely serves as a mechanical spacer to extend the focal plane, so it will not introduce chromatic aberration, astigmatism, or other distortions.

  • Barrel Size 1.25 inch
    Available Lengths 56mm
    Material CNC-machined aluminum
    Fits 1.25" focusers and eyepiece holders

    • SV157 1.25-inch Extension Tube

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  • SVBONY Warranty Policy