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Panny 20 aperture question

Discussion in 'Native Lenses' started by bbrovold, Mar 19, 2010.

  1. bbrovold

    bbrovold Mu-43 Rookie

    Feb 14, 2010
    Just got a Pan 20 1.7 and noticed something. The lens seems to keep a constant aperture of around 2.8 when at rest but when focusing it opens all the way and then stops back down (regardless of what is set for aperture). When actually taking the picture it stops to what is set like normal.
    Why would it be set up like this? Wouldn't wide open be the default at all times like an SLR? Can anyone else confirm this?
  2. ajramirez

    ajramirez Mu-43 Veteran

    Jan 16, 2010
    Caguas, Puerto Rico
    Mine behaves in exactly the same fashion. I do not know the reason why it works like that.

  3. BBW

    BBW Super Moderator Emeritus

    Hmm, this doesn't ring any bells for me...but maybe I'm so busy spinning that perpendicular wheel that I don't notice? So if you're in Aperture mode...and you are taking a photograph, are you saying the lens itself move on its own?
  4. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    Mine does the same thing, I never mentioned it because I figured that gremlins were doing something in there....
    Now I feel better knowing I'm not the only one with gremlin problems....
  5. BBW

    BBW Super Moderator Emeritus

    I must be blessed or living in an alternate reality...but hey, I don't notice the lens making noise either.:biggrin:
  6. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    It's a guy thing BB,
    Gremlins don't bother woman, just men...that's why we all take meds of some sort....
  7. BBW

    BBW Super Moderator Emeritus

    I need a shaking head, incredulous emoticon right about now, Don...but I believe you!
  8. bbrovold

    bbrovold Mu-43 Rookie

    Feb 14, 2010
    I think I figured it out. In more intense light the the effective aperture seemed smaller. I think the camera is varying the aperture to keep the EVF or display constant while viewing and then stopping down or changing to the actual aperture when taking the picture. IF that is the case it is a clever way to accomplish this but it would have been nice to know that instead of thinking something was wrong with the lens.
    I never noticed this with the 17 2.8 because the glass is just so darned small and I couldn't see the aperture blades.
  9. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    That seems very logical. Your probably right.
    I also never noticed on my 27 either.
    Maybe because it stays at 2.8 anyway.
    Thanks for dispelling the gremlin theory.
  10. PeterB666

    PeterB666 Mu-43 Top Veteran

    Jan 14, 2010
    Tura Beach, Australia
    It behaves that way on the Olympus cameras. Apart from making a little noise, there is no real issue there.

    My guess is that the Olympus is stopping the lens down to moderate the amount of light falling on the sensor for the LCD live view. As Olympus doesn't make anything faster than f/2.8 for the MFT cameas at the moment, it is hard to say what they are up to.
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