Boosting ISO versus post-processing underexposed images?

Discussion in 'Digital Photography' started by Walter Dnes (delete the 'z' to get my real address, Aug 18, 2005.

  1. I recently got a Panasonic FZ5. Great daylight camera in its niche,
    but sucks in low-light situations where you can't use flash. If I don't
    have a tripod, or I'm shooting anything but a building (i.e. any
    movement at all), I really need to keep shutter time to no more than
    1/100 second.

    This obviously leads to under-exposure in low-light situations. What
    doesn't help is that it can use f2.8 only if optical zoom isn't used.
    With optical zoom over 2X, it can't open up more than f3.2 or f3.3.

    I have a choice between switching to damn grainy ISO 400, versus
    taking a badly underexposed photo at ISO 80 and post-processing it in
    Gimp (or Photoshop or whatever). What's your experience as to which is
    the lesser of 2 evils? I would expect that post-processing would give
    better final results because you have more control over it and can use a
    powerful CPU versus whatever circuitry is on your camera.

    --
    Walter Dnes; my email address is *ALMOST* like
    Delete the "z" to get my real address. If that gets blocked, follow
    the instructions at the end of the 550 message.
     
    Walter Dnes (delete the 'z' to get my real address, Aug 18, 2005
    #1
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  2. Walter Dnes (delete the 'z' to get my real address) wrote:
    > I recently got a Panasonic FZ5. Great daylight camera in its niche,
    > but sucks in low-light situations where you can't use flash. If I
    > don't have a tripod, or I'm shooting anything but a building (i.e. any
    > movement at all), I really need to keep shutter time to no more than
    > 1/100 second.
    >
    > This obviously leads to under-exposure in low-light situations. What
    > doesn't help is that it can use f2.8 only if optical zoom isn't used.
    > With optical zoom over 2X, it can't open up more than f3.2 or f3.3.
    >
    > I have a choice between switching to damn grainy ISO 400, versus
    > taking a badly underexposed photo at ISO 80 and post-processing it in
    > Gimp (or Photoshop or whatever). What's your experience as to which
    > is the lesser of 2 evils? I would expect that post-processing would
    > give better final results because you have more control over it and
    > can use a powerful CPU versus whatever circuitry is on your camera.


    When faced with a similar situation recently, I ended up preferring the
    grainier images at the higher ISO. I suspect there are two issues here:

    - at low ISOs the darker areas may be irretrievably lost in JPEG
    compression. You could reduce such loss by using TIFF.

    - grain can add character to some images - providing a photo-journalistic
    look.

    Some cameras with a physically larger sensor (e.g. the 8.8 x 6.6mm sensor
    used in the Nikon 8800) may produce lower noise images, but Nikon makes
    the aperture at maximum zoom only f/4.9, more than killing any advantage.
    Fuji gets some good reports as well, but no image stabilisation. A DSLR
    has an even larger sensor, and would do well coupled to large aperture
    f/2.8, f/2 or f/1.4 lenses.

    You can also try resting your camera on an available surface or bean bag,
    to allow shake free exposures in the 1 second region, if your subjects
    allow this.

    However, like you I have an FZ5 rather than a DSLR, so I would look at
    programs like Paint Shop Pro 9 and Neat Image and use the rather effective
    noise reduction features provided. With care, a useful improvement can be
    obtained compared to the original image.

    Cheers,
    David
     
    David J Taylor, Aug 18, 2005
    #2
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  3. Walter Dnes (delete the 'z' to get my real address

    frederick Guest

    David J Taylor wrote:
    > Walter Dnes (delete the 'z' to get my real address) wrote:
    >
    >> I recently got a Panasonic FZ5. Great daylight camera in its niche,
    >>but sucks in low-light situations where you can't use flash. If I
    >>don't have a tripod, or I'm shooting anything but a building (i.e. any
    >>movement at all), I really need to keep shutter time to no more than
    >>1/100 second.
    >>
    >> This obviously leads to under-exposure in low-light situations. What
    >>doesn't help is that it can use f2.8 only if optical zoom isn't used.
    >>With optical zoom over 2X, it can't open up more than f3.2 or f3.3.
    >>

    There isn't much difference between f2.8 and f3.2 - it won't make a big
    difference to the shutter speed required to get the exposure right.
    >> I have a choice between switching to damn grainy ISO 400, versus
    >>taking a badly underexposed photo at ISO 80 and post-processing it in
    >>Gimp (or Photoshop or whatever). What's your experience as to which
    >>is the lesser of 2 evils? I would expect that post-processing would
    >>give better final results because you have more control over it and
    >>can use a powerful CPU versus whatever circuitry is on your camera.

    >
    >
    > When faced with a similar situation recently, I ended up preferring the
    > grainier images at the higher ISO. I suspect there are two issues here:
    >
    > - at low ISOs the darker areas may be irretrievably lost in JPEG
    > compression. You could reduce such loss by using TIFF.
    >

    I don't know if this would be very effective David - IIRC the Tiff files
    from that camera are 8 bit not 16 bit. (16 bit tiffs would be about
    40mb) When you try a large exposure correction, even dealing with 16 bit
    files, a large increase in noise is one of the first things you see, as
    well as loss of contrast, detail, and posterisation. Getting the
    exposure nailed as close to perfect is the best place to start for any
    post processing.

    > - grain can add character to some images - providing a photo-journalistic
    > look.
    >
    > Some cameras with a physically larger sensor (e.g. the 8.8 x 6.6mm sensor
    > used in the Nikon 8800) may produce lower noise images, but Nikon makes
    > the aperture at maximum zoom only f/4.9, more than killing any advantage.
    > Fuji gets some good reports as well, but no image stabilisation. A DSLR
    > has an even larger sensor, and would do well coupled to large aperture
    > f/2.8, f/2 or f/1.4 lenses.
    >
    > You can also try resting your camera on an available surface or bean bag,
    > to allow shake free exposures in the 1 second region, if your subjects
    > allow this.
    >
    > However, like you I have an FZ5 rather than a DSLR, so I would look at
    > programs like Paint Shop Pro 9 and Neat Image and use the rather effective
    > noise reduction features provided. With care, a useful improvement can be
    > obtained compared to the original image.
    >


    I haven't tried neat image. I haven't found any plugins for the Gimp
    that are very effective, and neat image seems to get good feedback from
    users.
     
    frederick, Aug 18, 2005
    #3
  4. frederick wrote:
    []
    >> - at low ISOs the darker areas may be irretrievably lost in JPEG
    >> compression. You could reduce such loss by using TIFF.
    >>

    > I don't know if this would be very effective David - IIRC the Tiff
    > files from that camera are 8 bit not 16 bit. (16 bit tiffs would be
    > about 40mb) When you try a large exposure correction, even dealing
    > with 16 bit files, a large increase in noise is one of the first
    > things you see, as well as loss of contrast, detail, and
    > posterisation. Getting the exposure nailed as close to perfect is
    > the best place to start for any post processing.


    I agree that there would be a great improvement, but any increase in dark,
    shadow detail may be welcome. The 8-bit TIFF are gamma-corrected (I
    presume), so would have the same dynamic range as the JPEG but without the
    loss. RAW as on the new Panasonic FZ30 would be better, of course.
    Even better, as you say, get the exposure right to start with!

    []
    > I haven't tried neat image. I haven't found any plugins for the Gimp
    > that are very effective, and neat image seems to get good feedback
    > from users.


    People who have compared say that Paint Shop Pro 9 is even better - you
    certainly have better control of the processing.

    Cheers,
    David
     
    David J Taylor, Aug 18, 2005
    #4
  5. Walter Dnes (delete the 'z' to get my real address

    frederick Guest

    David J Taylor wrote:
    > frederick wrote:
    > []
    >
    >>>- at low ISOs the darker areas may be irretrievably lost in JPEG
    >>>compression. You could reduce such loss by using TIFF.
    >>>

    >>
    >>I don't know if this would be very effective David - IIRC the Tiff
    >>files from that camera are 8 bit not 16 bit. (16 bit tiffs would be
    >>about 40mb) When you try a large exposure correction, even dealing
    >>with 16 bit files, a large increase in noise is one of the first
    >>things you see, as well as loss of contrast, detail, and
    >>posterisation. Getting the exposure nailed as close to perfect is
    >>the best place to start for any post processing.

    >
    >
    > I agree that there would be a great improvement, but any increase in dark,
    > shadow detail may be welcome. The 8-bit TIFF are gamma-corrected (I
    > presume), so would have the same dynamic range as the JPEG but without the
    > loss. RAW as on the new Panasonic FZ30 would be better, of course.
    > Even better, as you say, get the exposure right to start with!
    >
    > []
    >
    >>I haven't tried neat image. I haven't found any plugins for the Gimp
    >>that are very effective, and neat image seems to get good feedback
    >>from users.

    >
    >
    > People who have compared say that Paint Shop Pro 9 is even better - you
    > certainly have better control of the processing.
    >

    I am stunned at the effectiveness of noise reduction in raw processing
    using RSE. I haven't tried it on raw images from a compact camera, only
    a dslr. Separate luma and chroma sliders and being able to view a 100%
    crop as you adjust make fine-tuning it a breeze.
     
    frederick, Aug 18, 2005
    #5
  6. Walter Dnes (delete the 'z' to get my real address

    Jim Townsend Guest

    Walter Dnes (delete the 'z' to get my real address) wrote:

    > I recently got a Panasonic FZ5. Great daylight camera in its niche,
    > but sucks in low-light situations where you can't use flash. If I don't
    > have a tripod, or I'm shooting anything but a building (i.e. any
    > movement at all), I really need to keep shutter time to no more than
    > 1/100 second.
    >
    > This obviously leads to under-exposure in low-light situations. What
    > doesn't help is that it can use f2.8 only if optical zoom isn't used.
    > With optical zoom over 2X, it can't open up more than f3.2 or f3.3.


    Don't use the digital zoom. It's only a gimmick. You can digital
    zoom 'after the fact' by cropping and rescaling the result.

    >
    > I have a choice between switching to damn grainy ISO 400, versus
    > taking a badly underexposed photo at ISO 80 and post-processing it in
    > Gimp (or Photoshop or whatever). What's your experience as to which is
    > the lesser of 2 evils? I would expect that post-processing would give
    > better final results because you have more control over it and can use a
    > powerful CPU versus whatever circuitry is on your camera.
    >


    Post processing will work to some extent, but I find if images are
    too dark, when you lighten them, you bring out unwanted products such
    as streaks, color casts.

    There are post processing aids to remove the noise created at high ISO..
    Neat Image is one.. GIMP has a couple of 'denoiser' plug-ins. I can't
    say exactly what will work in your case, but I'd try both options and
    see which one produced the best results.
     
    Jim Townsend, Aug 18, 2005
    #6
  7. David J Taylor wrote:
    []
    > I agree that there would be a great improvement, but any increase in
    > dark, shadow detail may be welcome.


    Argh! Should be: I agree that there would not be a great improvement...
    (from using 8-bit TIFF versus JPEG).
     
    David J Taylor, Aug 18, 2005
    #7
  8. frederick wrote:
    []
    > I am stunned at the effectiveness of noise reduction in raw processing
    > using RSE. I haven't tried it on raw images from a compact camera,
    > only a dslr. Separate luma and chroma sliders and being able to view
    > a 100% crop as you adjust make fine-tuning it a breeze.


    I've not tested that myself, as I'm not generally a RAW user. With
    smaller sensor cameras you perhaps need an even more aggressive noise
    reduction, and this is where Paint Shop Pro 9 scores. It analyses the
    noise statistics at three different brightness levels in the images and
    then provides the sort of control you mention (although not separate
    luminance and chrominance control).

    Cheers,
    David
     
    David J Taylor, Aug 18, 2005
    #8
  9. On 18 Aug 2005 11:08:46 GMT, Walter Dnes (delete the 'z' to get my real address) <> wrote:
    > I recently got a Panasonic FZ5. Great daylight camera in its niche,
    > but sucks in low-light situations where you can't use flash. If I don't
    > have a tripod, or I'm shooting anything but a building (i.e. any
    > movement at all), I really need to keep shutter time to no more than
    > 1/100 second.


    1/100 seconds? That's a pretty short exposure time. Do you have the
    stabilizer turned on? With IS on, I can get fairly steady hand-held
    shots down to about 1/30 s at the long end of the zoom. Doesn't help if
    you're shooting a fast-moving object, of course, but does go a long way
    towards reducing camera shake limitations.

    > This obviously leads to under-exposure in low-light situations. What
    > doesn't help is that it can use f2.8 only if optical zoom isn't used.
    > With optical zoom over 2X, it can't open up more than f3.2 or f3.3.


    Are you sure? I'd have to check, but my recollection was that f2.8 was
    available fairly far up in the zoom range. In any case, f3.2 isn't that
    much smaller than f2.8.

    > I have a choice between switching to damn grainy ISO 400, versus
    > taking a badly underexposed photo at ISO 80 and post-processing it in
    > Gimp (or Photoshop or whatever). What's your experience as to which is
    > the lesser of 2 evils? I would expect that post-processing would give
    > better final results because you have more control over it and can use a
    > powerful CPU versus whatever circuitry is on your camera.


    I haven't done much low-light work with the FZ5, but so far, my
    preference goes:

    (1) Longer shutter time, constrained by camera shake and subject motion
    (2) Post processing
    (3) ISO boost, but I stop at 200

    -dms
     
    Daniel Silevitch, Aug 18, 2005
    #9
  10. On Thu, 18 Aug 2005 13:19:57 GMT, Daniel Silevitch, <> wrote:
    > On 18 Aug 2005 11:08:46 GMT, Walter Dnes (delete the 'z' to get my real address) <> wrote:


    > > movement at all), I really need to keep shutter time to no more than
    > > 1/100 second.

    >
    > 1/100 seconds? That's a pretty short exposure time. Do you have the
    > stabilizer turned on? With IS on, I can get fairly steady hand-held
    > shots down to about 1/30 s at the long end of the zoom. Doesn't help if
    > you're shooting a fast-moving object, of course, but does go a long way
    > towards reducing camera shake limitations.


    I run with IS mode 2 all the time. I'm talking about people who are
    not standing rigid for a portrait. I might get away with 1/60th on
    occasion, but 1/100th is better.

    --
    Walter Dnes; my email address is *ALMOST* like
    Delete the "z" to get my real address. If that gets blocked, follow
    the instructions at the end of the 550 message.
     
    Walter Dnes (delete the 'z' to get my real address, Aug 20, 2005
    #10
  11. On 20 Aug 2005 04:45:26 GMT, Walter Dnes (delete the 'z' to get my real address) <> wrote:
    > On Thu, 18 Aug 2005 13:19:57 GMT, Daniel Silevitch, <> wrote:
    >> On 18 Aug 2005 11:08:46 GMT, Walter Dnes (delete the 'z' to get my real address) <> wrote:

    >
    >> > movement at all), I really need to keep shutter time to no more than
    >> > 1/100 second.

    >>
    >> 1/100 seconds? That's a pretty short exposure time. Do you have the
    >> stabilizer turned on? With IS on, I can get fairly steady hand-held
    >> shots down to about 1/30 s at the long end of the zoom. Doesn't help if
    >> you're shooting a fast-moving object, of course, but does go a long way
    >> towards reducing camera shake limitations.

    >
    > I run with IS mode 2 all the time. I'm talking about people who are
    > not standing rigid for a portrait. I might get away with 1/60th on
    > occasion, but 1/100th is better.


    Got it. Then I would say first make sure that the aperture is wide open
    to maximize the amount of light that you do get. Check the live
    histogram; if there's no signal above about 1/4 or 1/3, consider upping
    the ISO, otherwise leave it alone and bring up the levels in post.

    -dms
     
    Daniel Silevitch, Aug 20, 2005
    #11
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