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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.
Shelyak C/CS Adapter Ring (5mm Spacer)

Shelyak C/CS Adapter Ring (5mm Spacer)

by Shelyak
SKU SHK-BA0036
$41.00 - $41.00
$41.00
$41.00 - $41.00
$41.00
Price Match Policy!
  • Provides 5mm of critical spacing
  • Adapts C-mount lenses for use on CS-mount cameras
  • Standard C-mount (male) to CS-mount (female) threads
  • Precision-machined metal construction for secure connection
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  • Description
  • FAQ
  • In the Box

  • C/CS Adapter Ring (5mm Spacer)

    This C/CS adapter ring provides the essential 5mm of spacing required to achieve perfect focus when using standard C-mount lenses on cameras with a CS-mount. Many modern astronomical guide cameras and planetary imagers use the CS-mount standard, which has a shorter flange-to-sensor distance than the C-mount standard common on security and industrial lenses.

    Bridge the 5mm Back Focus Gap for C-Mount Lenses

    C-mount lenses are designed to focus at a point farther away from the sensor than a native CS-mount camera can accommodate. Without correction, a C-mount lens will be unable to reach infinity focus on a CS-mount camera. This adapter ring acts as a simple, rigid 5mm extension that precisely bridges this mechanical gap, restoring the correct back focus.

    Installation is straightforward: simply thread the adapter onto your CS-mount camera body, and then thread your C-mount lens into the adapter. It's a fundamental accessory for anyone repurposing C-mount optics for astronomical imaging and is often paired with a T-mount to C-mount ring for connecting to a telescope's optical train.

  • What is this C/CS adapter ring used for?

    This is a 5mm spacer designed to let you use a C-mount lens on a CS-mount camera. It adds the necessary distance between the lens and the camera sensor to allow the lens to achieve proper focus, especially at infinity.

    Why do I need a 5mm spacer for a C-mount lens on my CS-mount camera?

    The C-mount and CS-mount standards have different back focus requirements—the required distance from the lens mounting flange to the sensor plane. C-mount lenses require a longer distance. This 5mm ring provides that exact amount of extra spacing needed for a C-mount lens to work correctly on a CS-mount body.

    Can I use this C/CS adapter ring to put a CS-mount lens on a C-mount camera?

    No, this adapter will not work for that purpose. A CS-mount lens needs to be closer to a C-mount sensor, but this adapter only adds distance. Attempting to use a CS-mount lens on a C-mount camera, even without an adapter, will typically result in an inability to reach focus.

    Will this 5mm C/CS adapter ring work with my ZWO ASI120MM Mini guide camera?

    Yes. The ZWO ASI120MM Mini, like many popular guide cameras, has a CS-mount. If you want to use a C-mount guide lens with it, you will need this 5mm C/CS adapter ring to achieve focus. This applies to most cameras that ship with a CS-mount as their primary interface.

    What happens if I don't use this C/CS adapter ring with my C-mount security lens?

    Without this 5mm adapter, your C-mount security or industrial lens will not be able to focus on a CS-mount camera. The image will be blurry because the lens cannot be moved far enough away from the sensor to form a sharp image. This ring is the essential component to make that combination work.

    How does this C/CS adapter ring work with a T-mount adapter?

    It's common to use a T-to-C-mount adapter to connect a CS-mount camera to a telescope focuser or other T-threaded accessory. In this setup, the 5mm C/CS ring would typically be threaded onto the camera first, followed by the T-to-C-mount adapter, ensuring all spacing requirements are met.

    • C/CS Adapter Ring

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