What causes aperture blades to close up during focusing (GF body)

Discussion in 'Panasonic Cameras' started by je83, Jun 20, 2013.

  1. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    I was testing this GF-3 on clearance today and I almost pulled the trigger when I noticed something peculiar. It seems the aperture blades would close up, not all the way but midway during focusing. I made sure to check that it wasn't in the Custom mode which allows for DOF preview and it wasn't. Also, the positioning of the blades didn't seem consistent with the chosen F-stop.

    They seemed to open up when taking shots, there was no card in the camera so I had little time to determine if they were properly exposed or not but what I saw from the quick previews seemed ok.

    Any clue as to what may be causing this? I don't have my own GF-3 with me now but I'm pretty sure I've never noticed this before. Maybe it's some kind of setting or metering mode that causes this, or maybe it's a mechanical thing with the blades themselves?

    Any input would be helpful. Thanks.
     
  2. Hagane

    Hagane Mu-43 Regular

    88
    May 31, 2013
    Limburg, Netherlands
    My G5 also does that, you probably tilted the camera upwards while standing under a light source.
    The G5 (and I think all Lumix cameras, can't speak for olympus) tends to leave the aperture fully open all the time to enable a smooth display rate. But in high light situations (standing under a lamp, outside on a sunny day) the aperture closes down a bit.
    To check your DOF you can always use the preview function which will open/close the aperture to the selected value.
     
  3. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    Thanks for that, I had no clue that's what happens. However, with the unit in question, I have also observed the aperture blades stay in the semi-closed position once turning the camera off.


    I just got home and I tried the light thing with my gf3. It only happened when I was right next to the window with really bright light. However, I tried the same thing in three other rooms to replicate the same light conditions as in the store, and i didn't get the shutter blades closing up even when I brought the camera right to the light.



    That makes sense, but you think it may also have something to do with the power options with the LCD or perhaps the setting that controls the auto brightness levels for it?

    BTW, it was kitted with 14 2.5 if that helps.
     
  4. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    Well I've been playing with my gf-3 a bit more since my last post and it seems, the different LCD brightness level settings have different sensitivities to light. I still can't get it to close up indoors with a light source from above like at the store but now it does close up when I put the camera right up to the light, which it didn't do before on the previous setting.

    The only thing now is I can't replicate the aperture blades staying closed once the camera is turned off, no matter what setting I try. Everytime I get them to close up and I turn the camera off, it opens up fully before cutting power.
    I'm pretty sure this is some sort of issue or defect, although I don't know if it's mechanical or software related and I don't really know how serious this issue is if it's something that can be corrected or fixed easily, since comes with a warranty, it's not a total deal breaker as of yet unless I find out it's an indication of a serious problem with the camera or lens.

    Any additional help or input with this would be appreciated.
     
  5. Hagane

    Hagane Mu-43 Regular

    88
    May 31, 2013
    Limburg, Netherlands
    With a faster lens the aperture closes down faster, with my 20mm 1.7 I can replicate this behavior indoors pretty easy.

    Not sure what to say about the blades staying put when powering off. On my G5 every lens goes to the fully open position when I turn off the camera and I'm pretty sure that this is the intended behavior...
     
  6. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    I really have to put my camera close to the light to get the same type reactions. I'm wondering maybe it's mine that has some defect.


    As far as the aperture blades, not fully open when the cam is shut, it could be some sort of electronic thing since I do remember once I turned it back on, they would open back up again and they didn't seem to interfere with taking shots, although I did only have about 3 mins or so to look at it.

    I don't think I've heard of cases where any m4/3 lenses have gotten stuck, but if it's a mechanical thing, I'm sure it's covered by the warranty.

    So basically, right now those are my two guesses, a software thing or a mechanical thing with the lens.
     
  7. RobR

    RobR Mu-43 Regular

    104
    Jun 19, 2013
    Connecticut, USA
    Robert Reinhardt
    This IS from a rookie photographer here, but I'll tell you an interesting story...
    Last weekend, I got myself my first Lumix lens (a 45-200mm) to go with my E-PL2. Half the day was spent trying to figure out what was binding and making a clicking sound when I zoomed in and out, until finally realizing it was the aperture blades changing position. What made it difficult was when I looked into the lens, the aperture would open up to full, and then I it was aimed at the sun, it would automatically stop down.
    Another time, I was photographing sunsets with a legacy OM 50mm f1.4 and I left the aperture wide open. The next day, there was a dark band which seemed to appear in all of my photos in the shape of the sunset and clouds. (Fortunately, it went away in a day or two.)
    Therefore, I come to the conclusion that this might have been programmed to prevent the sensor from being damaged. This does not happen with my Olympus lens, so I think it's a Lumix only thing.
     
  8. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    Thanks for the additional input. I was able to check out another GF-3 at a store today, similar conditions as with the first one, pointing it at a light source did not result in the the aperture blades closing up no matter how close to the lights I put the camera, I did get a few looks from the sales staff.

    Didn't get the aperture blades to stay semi-closed either when turning off. I don't really know if that confirms the presence of a defect or not but I will probably not get it. It would have been ok with the aperture closing up during focusing, which as you guys have explained could be due to the light (although mine and the one I tested today, don't seem to be as sensitive to it as the first one at the first store I tested), but the blades staying in the closed or semi-closed position when turned off seems like a more serious issue.
     
  9. entropicremnants

    entropicremnants Mu-43 All-Pro

    Jul 16, 2012
    John Griggs
    Focusing systems prefer a light level that maximizes contrast and signal to noise ratio. The camera will make decisions based on light levels and subject matter and so the aperture response can change from scene to scene. There can in fact be several different aperture settings for each of live view, focusing, and capturing the image.

    Don't over simplify modern contrast detection autofocus systems. To get these incredibly fast responses is more than just frame rate off the camera sensor -- they have a whole bag of tricks, lol.
     
  10. je83

    je83 Mu-43 Regular

    52
    Apr 16, 2013
    HKG
    Yeah, you guys are probably right about the apertures changing up, I just never really noticed until now.

    What do you make of the aperture blades staying in position and not opening up fully when turned off? Does it sound electronic or mechanical, is it enough of an issue that you would pass on the camera?