The plate on the D90 holder ring has some "mystery" threads I'm trying to figure out, see the attached picture.

Hole #1 is 1/4-20, typical tripod threads.

Hole #2 doesn't seem to work with either 6-32 or 6-36. Note that the provided socket screws that attach the plate to the ring measure 6-36, at least using my thread gauge, that seems to be the match. But those don't thread into these holes, nor do the 6-32 screws I have lying around.

Hole #3 is smaller yet, but it's not a 4-40. The 4-40 screws I have start to screw in but bind immediately.

So, what are the sized for those two holes?

  • w7ay replied to this.

    rbroberts Hole #2 doesn't seem to work with either 6-32 or 6-36.

    M4.

    Hole #3 is smaller yet, but it's not a 4-40.

    M3.

    Chen

      Which M3 and M4 threads?
      M4-0.7, M4-0.5?
      M3-0.35, M3-0.5, M3-0.6?

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