FD vs. FDn lens aperture ring question

Discussion in 'Adapted Lenses' started by Hyun, Feb 10, 2012.

  1. Hyun

    Hyun Mu-43 Regular

    Jan 20, 2012
    I have bought three FD-type lenses for my E-PM1 so far: 50mm f/1.4 SSC with breech lock mount, 28mm f/2.8 and 100-300mm f/5.6, both with bayonet mount. Got all from KEH.com.

    On the 50mm f/1.4 BL lens, I can adjust the aperture ring and see the aperture blades open or close. All is well. On the other two lenses, adjusting the aperture ring does nothing to the diaphragm blades. It's only when the lenses are mounted on the FD-to-m4/3 adapter, that I can adjust the aperture using the adapter's built-in open/lock aperture control ring.

    Is this how it's supposed to be? That unmounted, FDn lenses' aperture rings don't adjust the diaphragm blades as the FD(BL) lenses do?

    Here's my setup:


    (I know the aperture ring on the lens is set to "A", but I've tried it unlocked and all over the place)

    Thanks for any help.
  2. Luckypenguin

    Luckypenguin .

    Oct 9, 2010
    Brisbane, Australia
    Real Name:
    You've just described exactly how an FDn lens should work, so there is nothing wrong there. I'm actually a bit puzzled about the breech-lock lens, because the aperture still shouldn't engage when the lens is off the camera unless you rotate the breech and push the stop-down lever at the back of the lens.
  3. RDM

    RDM Mu-43 All-Pro

    Yes, that's is how its supposed to be. This is how mine work too. Except for one 135mm FD lens where the Pin in the adapter is maybe a millimeter too short to hit the aperture open pin.
  4. Hyun

    Hyun Mu-43 Regular

    Jan 20, 2012
    Oh, good. :). Thanks for clearing that up for me, guys.
  5. Grinch

    Grinch Mu-43 Top Veteran

    Jan 9, 2011
    Exactly what I was thinking. I believe your breech lock is on its way out, as it is not functioning as designed, it should not control aperture until adapter is in the locked position. Might want to question KEH for selling you a defective lens, depending on the rating put on that lens.
  6. Hyun

    Hyun Mu-43 Regular

    Jan 20, 2012
    Thanks. As it turns out I was mistaken--the 50mm f/1.4 BL lens, on its own, dismounted from the camera or lens adapter, doesn't do anything when the aperture ring is manipulated. The confusion (for me) came from the fact that once it's mounted, I could manipulate the aperture setting using the aperture ring on the lens, whereas with the other two lenses I have to use the adapter's aperture control to manipulate the diaphragm blades.

    Thanks for all the info!
  7. edmsnap

    edmsnap Mu-43 Veteran

    Dec 20, 2011
    Edmonton, Alberta
    That's not right either though. New or Old-Mount, once it's been properly hooked up to the adapter, the aperture ring should have control. The adapter should remain forever in the Lock position. I have both FD and nFD lenses and have never had to use the adapter's sliding-aperture control.