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C-mount to T-mount adapter ring
This C-mount to T-mount adapter ring physically connects two essential standards in astronomical and industrial imaging. It features a male M42x0.75mm T-thread on one side and a female internal 25.4mm C-mount thread on the other, providing a simple, rigid solution for integrating hardware that would otherwise be incompatible.
Connecting T-Mount Cameras to 25.4mm C-Mount Ports
The primary function of this adapter is to mount a camera with T-threads—such as a DSLR or a large-sensor astronomy camera—onto a C-mount port such as a guide port. This is a common requirement when using an off-axis guider's guide port, a microscope eyepiece port, or other specialized optical equipment that defaults to the smaller C-mount standard. This converter allows you to use your preferred, often larger, guide camera where only a C-mount was previously possible. Note that depending on your camera's sensor position, an additional C/CS-mount spacer ring may be required to achieve the correct back focus.
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What is the primary use for this C-mount to T-mount adapter ring?
Its main purpose is to mount a camera with T-threads (M42x0.75mm) on a C-mount (25.4mm) port: the ring has a male M42x0.75 thread on one side and a female 25.4mm C-mount thread on the other. This is most often used to connect a larger format guide camera to a smaller C-mount guide port on an off-axis guider or finderscope.
What are the exact thread specifications for this adapter ring?
The adapter has two distinct threads:
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Male Thread: M42x0.75mm, commonly known as T-mount or T2-mount.
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Female Thread: 25.4mm (1-inch) diameter with 32 threads per inch, which is the C-mount standard.
Can I use this adapter to attach my DSLR camera to a microscope C-mount port?
Yes, this is a valid application. If your DSLR has a standard T-ring attached (which provides a female M42x0.75mm thread), this adapter will allow you to screw it directly onto a C-mount photo port on a microscope, assuming you can achieve focus.
Will I need additional spacers for my guide camera to reach focus with this adapter ring?
Possibly. The C-mount standard has a flange-to-sensor distance of 17.526mm, while the related CS-mount is 12.5mm. If your guide camera is CS-mount native, you will likely need a 5mm C/CS spacer ring in the optical train to reach focus. This adapter does not change that fundamental spacing requirement.
Is this adapter the same as a T-ring for a camera?
No. A T-ring adapts a specific camera brand's lens mount (like Canon EF or Nikon F) to a female T-thread. This adapter has a male M42x0.75 T-thread on one side and a female 25.4mm C-mount thread on the other. You would typically use a T-ring on your camera first, and then attach this adapter to the T-ring.
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| Male Thread |
M42x0.75mm (T-mount) |
| Female Thread |
25.4mm x 32 TPI (C-mount) |
| Function |
Adapts T-mount (male) to C-mount (female) |
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C-mount to T-mount adapter ring
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- Shelyak 1-Year Warranty
