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GH2 14-140mm kit lens a hackable item?
  • davidp158davidp158

    I have the GH2 14-140mm kit lens, and I was wondering how the aperture interacts with the focal length while zooming. I understand that the 14-140mm lens isn't "constant apterture", but I was wondering if the aperture could be hacked to stay at one setting while zooming. If so, I could deal with the exposure changes in post. No doubt, a better lens with true constant aperture is preferred, but I just wondered if this was something that could be hacked like other areas of the GH2. Wishful thinking until I can afford better glass.

  • 11 Replies sorted by
  • ZedZed

    I don't think it's a software limitation. I guess it's the way the lens are built. The optical elements are not supposed to keep the same light power at the all zoom range. The physical aperture's size stays the same at all zoom ranges. Expensive lens with many kind of aspherical glass do have the same light power at all zoom ranges. That's what I always think about it.

  • balazerbalazer

    Zed, that's wrong. The 14-140 lens's aperture does not stay the same size at all focal lengths. It gets larger as you zoom in, though not quickly enough to maintain a constant f-number.

    And david, let's be clear if you're talking about a constant aperture or a constant f-number. They're not the same thing.

  • stoneystoney

    @balazer +1

  • davidp158davidp158

    balazer - Thanks for the clarification. I am not a photographer, so pardon my ignorance of proper terminology. If the aperture is controlled by electronics in the camera, I just wondered if there's a way to "hack" it to one aperture size (f-number?) so it wouldn't have the abrupt shifts. Of course, the light hitting the sensor will still diminish as the lens zooms out, but it may be easier to edit in post than the abrupt exposure shifts. For now, I'll zoom with my feet.

  • tuaniestuanies

    If you want it to not change aperture, set the aperture to F/5.8, which is the widest constant aperture you can have across the entire focal length. You cannot hack the lens to maintain F/4.0 because the lens and optics simply cannot do it.

  • balazerbalazer

    David,

    So you are talking about a constant aperture, not a constant f-number. That would require hacking, or simply disabling all of the lens's electronics by insulating its contacts.

    But if you just want to be able to zoom in and out without the abrupt changes in exposure that happen when the camera adjusts the aperture, you can achieve that by letting the camera control the shutter speed automatically: set the exposure mode to aperture priority, or full automatic. Using this particular lens, the camera is able to offset the abrupt changes in the aperture with a compensating adjustment in the shutter speed, synchronized so that you don't see any change in the exposure.

    BTW, when the lens extends as you zoom, that's called zooming in.

  • davidp158davidp158

    balazer - Thanks for your replies. I will try setting my camera to aperture priority and see how that works out.

    cheers - David

  • stoneystoney

    If aperture priority still gives noticeable stepping, try "P" exposure mode from movie recording menu. Shoot with Creative Movie mode.

  • questechquestech

    Hello Everyone,

    None of those solutions work. The lens adjusts the aperture on it's own, based on some algorithm in the firmware most likely, and it would be nice to cripple this "feature" if possible.

    I spoke with Panasonic tech support and the guy I spoke with had no clue as to what I was speaking about. He wanted me to send them the camera for testing... Ya Right.

    I asked him to escalate it to a level that I could actually speak with a technician (code for "Please let me speak to someone that knows what they're talking about") and he said he would and that someone would get back to me...

    That was the last I heard from them... So much for that.

    Yes, buying better glass is a solution, but I am really tiered of other people thinking they know what's good for me better than I do and then making choices for me.

    I can understand why they did this, but please don't :-)

  • Vitaliy_KiselevVitaliy_Kiselev

    Get http://www.ebay.com/itm/Canon-FD-80-200mm-F-4-L-Lens-MINT-/270974512279

    And save your time fighting your current lens :-)

  • balazerbalazer

    questech, you wouldn't like your 14-140 very much if it really had a constant aperture. f/4 at f=14 mm would be f/40 at f=140 mm. If you want a zoom with a constant f-number, you're going to pay for it, one way or another.

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