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William Optics 48mm T-Mount for Sony E - Black
William Optics 48mm T-Mount for Sony E - Black
William Optics 48mm T-Mount for Sony E - Black
William Optics 48mm T-Mount for Sony E - Black
William Optics 48mm T-Mount for Sony E - Black
William Optics 48mm T-Mount for Sony E - Black

William Optics 48mm T-Mount for Sony E - Black

by William Optics
SKU WO-TM-SN-E-M48
$55.00 - $55.00
$55.00
$55.00 - $55.00
$55.00
Price Match Policy!
  • Connects Sony E-mount cameras to M48 accessories
  • Provides a precise 36.7 mm optical length
  • M48 (female) threads reduce vignetting on large sensors
  • Durable, black anodized aluminum construction
  • Engineered for William Optics optical systems
3 in stock
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • William Optics 48mm T-Mount for Sony E - Black

    Securely connect your Sony E-mount camera to your telescope's M48 corrector or flattener with the William Optics 48mm T-Mount for Sony E. This adapter provides a precise optical length of 36.7 mm, critical for achieving a perfectly flat field with William Optics imaging systems. Its female M48 threads create a wide, unvignetted light path directly to your camera's sensor, eliminating the bottleneck caused by older M42 T-rings.

    M48 Threading: A Wider, 36.7mm Path for Full-Frame Sony Sensors

    This T-mount is engineered specifically for modern astrophotography setups that utilize full-frame or large APS-C sensors, common in the Sony Alpha camera line. The M48 (2-inch filter) thread provides a larger clear aperture than the standard M42 T-thread, ensuring the corrected light cone from your flattener fully illuminates the sensor without clipping the corners of the frame.

    The fixed 36.7 mm optical length is not arbitrary; it is calculated to achieve the exact back focus required by many William Optics flatteners and reducers when paired with a Sony E-mount camera. This single-piece design removes the guesswork and potential for tilt introduced by using multiple extension tubes, resulting in sharper stars across your entire image.

    M48 vs. M42 T-Rings: The 6mm Difference for Full-Frame Imaging

    For decades, the M42 "T-ring" was the standard for connecting cameras to telescopes. However, its 42mm clear aperture acts as a choke point for the light path, causing significant vignetting (darkened corners) on sensors larger than the APS-C format. A full-frame sensor simply cannot be fully illuminated through such a narrow opening.

    The William Optics 48mm T-Mount solves this problem. By expanding the connection thread to M48, it creates a wider gateway for light, preserving the field illumination your telescope's corrector was designed to deliver. If you are imaging with a full-frame Sony camera, an M48 T-mount is essential for maximizing the usable area of your sensor and capturing clean, evenly illuminated frames.

  • What is the purpose of the William Optics 48mm T-Mount for Sony E?

    This T-mount serves one primary function: to connect a Sony E-mount camera (such as those in the Alpha series) to a telescope flattener, reducer, or other accessory that uses a male M48x0.75 thread. It also sets the camera sensor at a precise 36.7 mm distance from the accessory's threads, which is critical for achieving correct back focus.

    Why should I choose this M48 T-Mount over a standard M42 T-ring for my Sony A7?

    A standard M42 T-ring has a smaller opening that will cause significant vignetting (darkened corners) on the full-frame sensor of a Sony A7 series camera. The larger M48 thread on this William Optics mount provides a wider light path, ensuring the entire sensor is evenly illuminated, which is crucial for high-quality, wide-field astrophotography.

    Is the 36.7 mm optical length of this T-Mount important?

    Yes, it is extremely important. Most field flatteners and reducers require a specific back focus distance (typically 55mm) to produce sharp stars across the entire field. Sony E-mount cameras have a flange distance of 18mm. This adapter's 36.7 mm length, when added to the camera's 18mm, totals 54.7mm—very close to the 55mm standard. It is specifically designed to achieve perfect spacing with many William Optics correctors.

    Which William Optics telescopes is this 48mm T-Mount designed for?

    This T-mount is compatible with any William Optics telescope that uses a field flattener or reducer terminating in a male M48 thread. This includes popular models such as:

    • RedCat, WhiteCat, and SpaceCat series refractors
    • Fluorostar (FLT) series with their corresponding flatteners
    • Gran Turismo (GT) series with their corresponding flatteners

    Always check your specific flattener's documentation to confirm it requires an M48 connection and is compatible with the resulting back focus.

    Will this T-mount work for imaging the Andromeda Galaxy (M31) with my full-frame Sony camera?

    Yes, this is an ideal accessory for that exact scenario. The Andromeda Galaxy is a very large target, and a full-frame sensor is needed to capture it fully with many refractors. Using this 48mm T-Mount ensures that the faint outer spiral arms of M31 are not dimmed or cut off by vignetting, which would almost certainly happen with a smaller M42 T-ring.

    How do I attach the WO 48mm T-Mount to my imaging train?

    First, remove the lens from your Sony E-mount camera. Align the indicator dot on the T-mount with the dot on your camera's bayonet mount and twist to lock it in place, just like a standard lens. Then, you can thread the entire camera and T-mount assembly directly onto the male M48 threads of your telescope's field flattener or reducer.

  • Connection to Telescope M48 x 0.75 Female Thread
    Connection to Camera Sony E-Mount (NEX/Alpha)
    Optical Length / Back Focus Contribution 36.7 mm

    • William Optics 48mm T-Mount for Sony E

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  • William Optics 2-Year Warranty