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Adapter Ring for Canon EOS to T-Mount (M42x0.75)
This adapter ring connects a T-mount camera (M42x0.75) to the Canon EOS lens of the Shelyak eShel fiber-fed spectroscopy system. The ring is 9 mm thick.
Connect a T-Mount Camera to the eShel Canon EOS Lens
The eShel spectroscope focuses its echelle spectrum on the camera through a Canon EOS lens. Shelyak recommends mounting the CCD acquisition camera on this lens with the proper adapter, and this ring (BA0023) is that adapter for T-mount cameras such as the QSI516ws or QSI532ws.
To mount a Canon EOS camera body on a T-threaded instrument instead, use the complementary T-Mount to Canon EOS DSLR Adapter Ring (BA0043).
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What is the primary function of this Adapter ring EOS / T-mount?
It connects a T-mount (M42x0.75) camera to a Canon EOS lens, as used on the Shelyak eShel spectroscope, where it holds the acquisition camera on the eShel objective lens.
Can I use this ring to attach a Canon EOS camera body to my telescope?
No. This ring mounts a T-mount camera on a Canon EOS lens. To attach a Canon EOS camera body to a T-threaded instrument, use the T-Mount to Canon EOS DSLR Adapter Ring (BA0043).
How is the eShel lens focused with this ring?
By hand. Shelyak focuses the eShel Canon EOS lens on a Thorium-Argon spectrum: you simply turn the lens to focus, adjusting it to minimize the width of an isolated emission line.
What accessories besides a telescope use the M42x0.75 T-mount thread?
The M42x0.75 T-thread is a common standard in astronomy, found on accessories such as:
- Filter wheels and filter drawers
- Off-axis guiders (OAGs)
- Field flatteners and focal reducers
- Coma correctors
- Extension tubes for adjusting back focus
Does this ring fit on a Canon EOS camera body?
No. This ring takes the place of the camera body on a Canon EOS lens: the lens mounts on the ring and the T-mount camera attaches to the ring. To mount a Canon EOS camera body on a T-threaded instrument, use the T-Mount to Canon EOS DSLR Adapter Ring (BA0043).
Do I need anything else to connect my camera to a 2" focuser using this adapter?
No. This ring is not a telescope adapter. It joins a T-mount camera to the Canon EOS lens of the eShel spectroscope; the eShel system connects to the telescope through its Fiber Injection and Guiding Unit (FIGU) and optical fiber.
