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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.
Player One M42F-M42M Adapter - 20mm
Player One M42F-M42M Adapter - 20mm

Player One M42F-M42M Adapter - 20mm

by Player One
SKU POA-M42F-M42M-20
$24.00 - $24.00
$24.00
$24.00 - $24.00
$24.00
Price Match Policy!
  • Provides a fixed 20mm spacing extension
  • Female Thread: M42 x 0.75
  • Male Thread: M42 x 0.75
  • Corrects back focus for flatteners and reducers
  • Standard T-Thread compatibility
2 in stock
Qualifies for FREE Shipping in CONUS on orders over $350.
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Player One M42F-M42M Adapter - 20mm

    The Player One M42F-M42M Adapter provides a fixed 20mm extension for standard M42x0.75 threaded imaging trains. This 20mm spacer is an essential component for achieving the precise back focus distance specified by field flatteners and focal reducers, ensuring sharp, well-corrected stars across the entire image frame.

    Precision 20mm M42 Extension for Back Focus Tuning

    The primary function of a 20mm extension is to correctly set the distance between your camera's sensor and an optical corrector. Most flatteners and reducers require a specific back focus, often 55mm, and this adapter helps bridge the gap between your camera's native flange distance and that critical target measurement.

    • Back Focus Correction: Adds a fixed 20mm to your optical train, making it a key part of the calculation for hitting the 55mm standard or other custom spacing requirements.
    • Accessory Spacing: Creates necessary clearance between components, such as preventing a filter wheel from colliding with a focuser or a large camera body.
    • Universal T-Threads: Utilizes the M42x0.75 thread standard (also known as T-threads or T2), ensuring broad compatibility with nearly all dedicated astronomy cameras, filter wheels, and off-axis guiders.

  • How do I use the Player One 20mm M42 adapter to achieve 55mm of back focus?

    You use it as part of the total back focus calculation. For example, if your camera has a 17.5mm flange distance, you would add this 20mm adapter plus another 17.5mm of spacers to reach the required 55mm (17.5 + 20 + 17.5 = 55). It provides a solid, single component for a significant portion of that distance.

    My flattener needs 55mm back focus and my camera has 17.5mm. What else do I need with this 20mm adapter?

    After accounting for your camera (17.5mm) and this adapter (20mm), you have used 37.5mm of the required 55mm. You would need an additional 17.5mm of spacers (55 - 37.5 = 17.5) to complete the imaging train.

    What are the threads on the Player One 20mm Adapter?

    The adapter features standard M42x0.75 T-threads. It has male threads on one side and female threads on the other, serving as a direct, straight-through extension.

    Can I stack multiple Player One 20mm adapters?

    Yes, you can thread multiple adapters together to create longer extensions (e.g., two for 40mm). However, for longer distances, using a single, longer extension tube is generally recommended to maximize rigidity and minimize potential flexure in the imaging train.

    Is this Player One adapter threaded for 1.25" or 2" filters?

    No, this is a spacing adapter only. It does not have internal threads for mounting filters. Filters must be placed elsewhere in the optical train, such as in a filter wheel or a dedicated filter drawer.

    What is the difference between an M42 adapter and a T2 adapter?

    There is no difference in this context. The terms M42, T-thread, and T2-thread all refer to the same M42x0.75mm thread specification, which is the de facto standard for astrophotography equipment. This adapter is compatible with all of them.

  • Extension Length 20mm
    Female Thread M42 x 0.75 (T2-thread)
    Male Thread M42 x 0.75 (T2-thread)

    • Player One M42F-M42M Adapter - 20mm

      × 1

  • Player One 2-Year Warranty