Long exposure, processing time on Lumix

Discussion in 'Panasonic Lumix' started by Wills, Sep 13, 2005.

  1. Wills

    Wills Guest

    I have a Panasonic Lumix DMC-FZ20 camera and have been taking some long
    exposure shots of 8 second (lightning).

    The camera take another 8 seconds to process the pictures (at which time the
    lightning strikes!)

    Can anyone explain why this is, and do all digital cameras behave the same?
    If not then which are the fatest.

    Ta
     
    Wills, Sep 13, 2005
    #1
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  2. Wills

    Aad Guest

    "Wills" <> schreef in bericht
    news:...
    >I have a Panasonic Lumix DMC-FZ20 camera and have been taking some long
    > exposure shots of 8 second (lightning).
    >
    > The camera take another 8 seconds to process the pictures (at which time
    > the
    > lightning strikes!)
    >
    > Can anyone explain why this is, and do all digital cameras behave the
    > same?
    > If not then which are the fatest.
    >
    > Ta


    It's prob. to do with (in camera) long exposure noise reduction.
    Turn it off and look at the differences.
    Aad
     
    Aad, Sep 13, 2005
    #2
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  3. Wills

    John Bean Guest

    On Tue, 13 Sep 2005 11:14:13 +0100, Wills
    <> wrote:

    >I have a Panasonic Lumix DMC-FZ20 camera and have been taking some long
    >exposure shots of 8 second (lightning).
    >
    >The camera take another 8 seconds to process the pictures (at which time the
    >lightning strikes!)
    >
    >Can anyone explain why this is, and do all digital cameras behave the same?
    >If not then which are the fatest.


    It's a technique called "dark frame subtraction", and most
    cameras do this for long exposures. The noise generated by
    the sensor builds up as the time increases in a way that's
    consistent for the particular sensor in the particular
    situation in which it's being used. After the "real"
    exposure finishes the camera makes another identical
    exposure but with the shutter closed - the "dark frame" -
    which has the same noise pattern as the real exposure. This
    is then subtracted from the original, cancelling most of the
    noise without hurting the image detail.


    --
    Regards

    John Bean
     
    John Bean, Sep 13, 2005
    #3
  4. Wills

    News Will Guest

    Thanks. That's something on the lines I was thinking.
    Unfortunaly it's not possible to switch off noise reduction, reducing it
    does nothing.

    I have a friend who has a Nikon D100, which gives control back 'immediately
    it finishes saving, but there's no way I can afford a D100 and the selection
    of lenses of 35 -400mm equiv!

    However I do have a wide selection of Pentax lens, so if some kind reader
    has a Pentax *ist DS, perhaps they could let know if there is a considerable
    recoverey time on on of these cameras.

    Thanks
    > > I have a Panasonic Lumix DMC-FZ20 camera and have been taking some long
    > > exposure shots of 8 second (lightning).
    > >
    > > The camera take another 8 seconds to process the pictures (at which time
    > > the lightning strikes!)
    > >
    > > Can anyone explain why this is, and do all digital cameras behave the
    > > same? If not then which are the fatest.

    >
    > It's a technique called "dark frame subtraction", and most cameras do this
    > for long exposures. The noise generated by the sensor builds up as the
    > time increases in a way that's consistent for the particular sensor in the
    > particular situation in which it's being used. After the "real" exposure
    > finishes the camera makes another identical exposure but with the shutter
    > closed - the "dark frame" - which has the same noise pattern as the real
    > exposure. This is then subtracted from the original, cancelling most of
    > the noise without hurting the image detail.
    >
    >
     
    News Will, Sep 15, 2005
    #4
  5. Wills

    John Bean Guest

    On Thu, 15 Sep 2005 17:06:14 +0100, News Will
    <> wrote:
    >However I do have a wide selection of Pentax lens, so if some kind reader
    >has a Pentax *ist DS, perhaps they could let know if there is a considerable
    >recoverey time on on of these cameras.


    I also have a DS :)

    Dark frame subtraction is done by default for exposures
    longer than a second but it can be turned off if you so
    desire - first item in the Custom Menu: "Noise rediction"
    on/off.


    --
    Regards

    John Bean
     
    John Bean, Sep 15, 2005
    #5
  6. Wills

    News Will Guest

    John Bean <> wrote:

    > I also have a DS :)


    I DON'T have a DS, but am considering getting one.

    Perhaps you can tell me, how long after a 8+second exposure, before you can
    take another picture.

    > Dark frame subtraction is done by default for exposures longer than a
    > second but it can be turned off if you so desire - first item in the
    > Custom Menu: "Noise rediction" on/off.

    Unfortunately this is not available on the Lumix

    Ta
     
    News Will, Sep 15, 2005
    #6
  7. Wills

    John Bean Guest

    On Thu, 15 Sep 2005 18:42:56 +0100, News Will
    <> wrote:

    >John Bean <> wrote:
    >
    >> I also have a DS :)

    >
    >I DON'T have a DS, but am considering getting one.


    I used "also" because I have a DS as well as a Panasonic,
    not because I thought you had a DS.

    >
    >Perhaps you can tell me, how long after a 8+second exposure, before you can
    >take another picture.


    I thought I already had. I already explained that the delay
    is caused by the dark frame subtraction (noise reduction)
    process, so ...

    >
    >> Dark frame subtraction is done by default for exposures longer than a
    >> second but it can be turned off if you so desire - first item in the
    >> Custom Menu: "Noise rediction" on/off.


    .... if you turn it off there's no delay. Hope that's
    clearer.

    >Unfortunately this is not available on the Lumix


    Yes, but you asked about the DS...

    --
    Regards

    John Bean
     
    John Bean, Sep 15, 2005
    #7
  8. Wills

    News Will Guest

    [Posted and mailed]

    John Bean <> wrote:

    > On Thu, 15 Sep 2005 18:42:56 +0100, News Will <>
    > wrote:
    >
    > > John Bean <> wrote:
    > >
    > > > I also have a DS :)

    > >
    > > I DON'T have a DS, but am considering getting one.

    >
    > I used "also" because I have a DS as well as a Panasonic, not because I
    > thought you had a DS.
    >
    > >
    > > Perhaps you can tell me, how long after a 8+second exposure, before you
    > > can take another picture.

    >
    > I thought I already had. I already explained that the delay is caused by
    > the dark frame subtraction (noise reduction) process, so ...
    >
    > >
    > > > Dark frame subtraction is done by default for exposures longer than a
    > > > second but it can be turned off if you so desire - first item in the
    > > > Custom Menu: "Noise rediction" on/off.

    >
    > ... if you turn it off there's no delay. Hope that's clearer.
    >
    > > Unfortunately this is not available on the Lumix

    >
    > Yes, but you asked about the DS...


    It's been a long hot sticky day!
    Thanks very much, I hope to have a DS soon :)

    Willie
     
    News Will, Sep 15, 2005
    #8
  9. Wills

    News Will Guest

    John Bean <> wrote:

    > On Thu, 15 Sep 2005 18:42:56 +0100, News Will <>
    > wrote:
    >
    > > John Bean <> wrote:
    > >
    > > > I also have a DS :)

    > >
    > > I DON'T have a DS, but am considering getting one.

    >
    > I used "also" because I have a DS as well as a Panasonic, not because I
    > thought you had a DS.
    >
    > >
    > > Perhaps you can tell me, how long after a 8+second exposure, before you
    > > can take another picture.

    >
    > I thought I already had. I already explained that the delay is caused by
    > the dark frame subtraction (noise reduction) process, so ...
    >
    > >
    > > > Dark frame subtraction is done by default for exposures longer than a
    > > > second but it can be turned off if you so desire - first item in the
    > > > Custom Menu: "Noise rediction" on/off.

    >
    > ... if you turn it off there's no delay. Hope that's clearer.
    >
    > > Unfortunately this is not available on the Lumix

    >
    > Yes, but you asked about the DS...


    It's been a long hot sticky day!
    Thanks very much, I hope to have a DS soon :)

    Willie
     
    News Will, Sep 15, 2005
    #9
  10. Wills

    John Bean Guest

    On Thu, 15 Sep 2005 19:27:20 +0100, News Will
    <> wrote:
    >It's been a long hot sticky day!


    I blame age when I do it :)

    >Thanks very much, I hope to have a DS soon :)


    It's a nice camera, you'll like it - especially if you
    already have some nice Pentax lenses.


    --
    Regards

    John Bean
     
    John Bean, Sep 15, 2005
    #10
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