Polarizers and digital

Discussion in 'Digital Photography' started by Geoff Bryant, Jan 3, 2004.

  1. Geoff Bryant

    Geoff Bryant Guest

    After many years shooting transparency film I made the switch to digital
    last August. I'm more than happy with the results but one thing intrigues me
    and perhaps someone here can enlighten me.

    Clearly cameras follow the same optical laws regardless of the capture
    medium, but I've noticed that with digital filters seems to have less
    effect.

    I can understand this with coloured filters that may be negated somewhat by
    automatic white balance, but what intrigues me is how the virtual trade mark
    effect of a polarizer - deep blue to almost black skies - seems so much
    reduced.

    Yesterday I took some test shots with my 10D. It's midsummer here in the
    southern hemisphere and the sky was clear blue with a just a very few pure
    white clouds. The polarized shots certainly showed sharper contrast between
    the clouds and the sky and the colours of the grass and other foliage were
    brighter because of the reduced reflection. However, the colour of the sky
    hardly changed; certainly not to the extent that I observed through the
    viewfinder. With film it would probably have gone the other way - a far
    greater effect.

    Is this really the case or am I missing something?

    Geoff Bryant
    www.hortiphoto.com
     
    Geoff Bryant, Jan 3, 2004
    #1
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  2. Geoff Bryant

    Don Coon Guest

    "Geoff Bryant" <> wrote in message
    news:N_qJb.57$...
    > After many years shooting transparency film I made the switch to digital
    > last August. I'm more than happy with the results but one thing intrigues

    me
    > and perhaps someone here can enlighten me.
    >
    > Clearly cameras follow the same optical laws regardless of the capture
    > medium, but I've noticed that with digital filters seems to have less
    > effect.
    >
    > I can understand this with coloured filters that may be negated somewhat

    by
    > automatic white balance, but what intrigues me is how the virtual trade

    mark
    > effect of a polarizer - deep blue to almost black skies - seems so much
    > reduced.
    >
    > Yesterday I took some test shots with my 10D. It's midsummer here in the
    > southern hemisphere and the sky was clear blue with a just a very few pure
    > white clouds. The polarized shots certainly showed sharper contrast

    between
    > the clouds and the sky and the colours of the grass and other foliage were
    > brighter because of the reduced reflection. However, the colour of the sky
    > hardly changed; certainly not to the extent that I observed through the
    > viewfinder. With film it would probably have gone the other way - a far
    > greater effect.
    >
    > Is this really the case or am I missing something?
    >
    > Geoff Bryant
    > www.hortiphoto.com


    Not sure if you're missing anything but I must say a circular polarizer
    works well on my 10D --- sometimes too well : ) --- skies that are too
    blue. Keep working with it; it works. Now, if you could just send some of
    that nice summer sun North -- it's dark by 5 PM her in the northern 48 of
    the USA.
     
    Don Coon, Jan 3, 2004
    #2
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  3. Geoff Bryant

    Jim Townsend Guest

    Geoff Bryant wrote:

    > After many years shooting transparency film I made the switch to digital
    > last August. I'm more than happy with the results but one thing intrigues me
    > and perhaps someone here can enlighten me.
    >
    > Clearly cameras follow the same optical laws regardless of the capture
    > medium, but I've noticed that with digital filters seems to have less
    > effect.


    Are you using a circular polarizer ?? If so, you shouldn't see any
    difference. All the 'polarizing' is done before the light hits the film or
    sensor.

    I have a 10D and use a polarizer now and then.. Just as Don Coon indicates..
    They work fine on digicams..
     
    Jim Townsend, Jan 3, 2004
    #3
  4. Geoff Bryant

    Geoff Bryant Guest

    Yes, I'm using a circular polarizer. And yes, it works. But although I can
    see the effect, it doesn't seem nearly as extreme as with film, where the
    sky well above the horizon can become a really deep indigo blue. That
    doesn't worry me, as that is usually too way over the top to be much use,
    but it does interest me because as you say, all of that happens before the
    light hits the sensor.

    I was wondering if perhaps the CMOS sensor's need to do some nearest
    neighbour colour interpolation was perhaps partly offsetting the effect of
    the polarizer.

    I have to admit the difference is subtle, but compare the deep blue in the
    top right corner of www.hortiphoto.com/pages/TRE0118.shtml with the mid-blue
    of www.hortiphoto.com/pages2/TRE0230.shtml. Another shot
    www.hortiphoto.com/pages2/SCH0017.shtml shows how the polarizer still works
    well to increase contrast in what otherwise be a rather monochrome scene, so
    I won't be ditching it just yet.

    Geoff Bryant
    www.hortiphoto.com


    "Jim Townsend" <> wrote in message
    news:...
    > Geoff Bryant wrote:
    >
    > > After many years shooting transparency film I made the switch to digital
    > > last August. I'm more than happy with the results but one thing

    intrigues me
    > > and perhaps someone here can enlighten me.
    > >
    > > Clearly cameras follow the same optical laws regardless of the capture
    > > medium, but I've noticed that with digital filters seems to have less
    > > effect.

    >
    > Are you using a circular polarizer ?? If so, you shouldn't see any
    > difference. All the 'polarizing' is done before the light hits the film

    or
    > sensor.
    >
    > I have a 10D and use a polarizer now and then.. Just as Don Coon

    indicates..
    > They work fine on digicams..
    >
    >
     
    Geoff Bryant, Jan 3, 2004
    #4
  5. Geoff Bryant

    Jim Davis Guest

    Try shooting at 90 degrees to the sun and rotate your filter for
    maximum effect. This is how you will see the maximum effect. However,
    different days, different effects. I have noticed a dramatic effect on
    folliage, which is what I need the CP for, not making blue skies
    darker. I can do that, any nurealistic blue skies which I like. If I
    want more saturation, I crank up the saturation. Skies are usually
    easy enough to mask as well.

    I'm using Capture One and that really helps.

    On Sat, 3 Jan 2004 13:19:53 +1300, "Geoff Bryant"
    <> wrote/replied to:

    >After many years shooting transparency film I made the switch to digital
    >last August. I'm more than happy with the results but one thing intrigues me
    >and perhaps someone here can enlighten me.
    >
    >Clearly cameras follow the same optical laws regardless of the capture
    >medium, but I've noticed that with digital filters seems to have less
    >effect.
    >
    >I can understand this with coloured filters that may be negated somewhat by
    >automatic white balance, but what intrigues me is how the virtual trade mark
    >effect of a polarizer - deep blue to almost black skies - seems so much
    >reduced.
    >
    >Yesterday I took some test shots with my 10D. It's midsummer here in the
    >southern hemisphere and the sky was clear blue with a just a very few pure
    >white clouds. The polarized shots certainly showed sharper contrast between
    >the clouds and the sky and the colours of the grass and other foliage were
    >brighter because of the reduced reflection. However, the colour of the sky
    >hardly changed; certainly not to the extent that I observed through the
    >viewfinder. With film it would probably have gone the other way - a far
    >greater effect.
    >
    >Is this really the case or am I missing something?
    >
    >Geoff Bryant
    >www.hortiphoto.com
    >
    >
    >
     
    Jim Davis, Jan 3, 2004
    #5
  6. Geoff Bryant

    Tony Spadaro Guest

    Are your film shots mostly on slide film? If so do you tend to under-expose
    for greater saturation, or use a high saturation film?
    That's teh only difference I can think of.

    --
    http://www.chapelhillnoir.com
    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    http://www.chapelhillnoir.com/links/mlinks00.html
    A sample chapter from my novel "Haight-Ashbury" is at
    http://www.chapelhillnoir.com/writ/hait/hatitl.html
    "Geoff Bryant" <> wrote in message
    news:8OrJb.88$...
    > Yes, I'm using a circular polarizer. And yes, it works. But although I

    can
    > see the effect, it doesn't seem nearly as extreme as with film, where the
    > sky well above the horizon can become a really deep indigo blue. That
    > doesn't worry me, as that is usually too way over the top to be much use,
    > but it does interest me because as you say, all of that happens before the
    > light hits the sensor.
    >
    > I was wondering if perhaps the CMOS sensor's need to do some nearest
    > neighbour colour interpolation was perhaps partly offsetting the effect of
    > the polarizer.
    >
    > I have to admit the difference is subtle, but compare the deep blue in the
    > top right corner of www.hortiphoto.com/pages/TRE0118.shtml with the

    mid-blue
    > of www.hortiphoto.com/pages2/TRE0230.shtml. Another shot
    > www.hortiphoto.com/pages2/SCH0017.shtml shows how the polarizer still

    works
    > well to increase contrast in what otherwise be a rather monochrome scene,

    so
    > I won't be ditching it just yet.
    >
    > Geoff Bryant
    > www.hortiphoto.com
    >
    >
    > "Jim Townsend" <> wrote in message
    > news:...
    > > Geoff Bryant wrote:
    > >
    > > > After many years shooting transparency film I made the switch to

    digital
    > > > last August. I'm more than happy with the results but one thing

    > intrigues me
    > > > and perhaps someone here can enlighten me.
    > > >
    > > > Clearly cameras follow the same optical laws regardless of the capture
    > > > medium, but I've noticed that with digital filters seems to have less
    > > > effect.

    > >
    > > Are you using a circular polarizer ?? If so, you shouldn't see any
    > > difference. All the 'polarizing' is done before the light hits the film

    > or
    > > sensor.
    > >
    > > I have a 10D and use a polarizer now and then.. Just as Don Coon

    > indicates..
    > > They work fine on digicams..
    > >
    > >

    >
    >
    >
     
    Tony Spadaro, Jan 3, 2004
    #6
  7. In article <N_qJb.57$>,
    "Geoff Bryant" <> wrote:

    > After many years shooting transparency film I made the switch to digital
    > last August. I'm more than happy with the results but one thing intrigues me
    > and perhaps someone here can enlighten me.
    >
    > Clearly cameras follow the same optical laws regardless of the capture
    > medium, but I've noticed that with digital filters seems to have less
    > effect.
    >
    > I can understand this with coloured filters that may be negated somewhat by
    > automatic white balance, but what intrigues me is how the virtual trade mark
    > effect of a polarizer - deep blue to almost black skies - seems so much
    > reduced.
    >
    > Yesterday I took some test shots with my 10D. It's midsummer here in the
    > southern hemisphere and the sky was clear blue with a just a very few pure
    > white clouds. The polarized shots certainly showed sharper contrast between
    > the clouds and the sky and the colours of the grass and other foliage were
    > brighter because of the reduced reflection. However, the colour of the sky
    > hardly changed; certainly not to the extent that I observed through the
    > viewfinder. With film it would probably have gone the other way - a far
    > greater effect.
    >
    > Is this really the case or am I missing something?
    >
    > Geoff Bryant
    > www.hortiphoto.com
    >


    A polarizer's effect is extremely dependent on the weather and the angle
    of the sun. There are times when the sky is black 90 deg from the sun
    and there are times when nothing happens at all. It all depends on
    where the scattering of light happens and where the sun is relative to
    your subject. Just a little bit of low altitude haze can completely
    depolarize light from the sky.

    You can try a fixed white balance just to make sure it's not a camera
    issue but I'm guessing it was just a bad day for a polarizer.
     
    Kevin McMurtrie, Jan 3, 2004
    #7
  8. "Geoff Bryant" <> writes:

    >I can understand this with coloured filters that may be negated somewhat by
    >automatic white balance, but what intrigues me is how the virtual trade mark
    >effect of a polarizer - deep blue to almost black skies - seems so much
    >reduced.


    What happens if you disable the auto white balance, then shoot with and
    without a polarizer?

    Dave
     
    Dave Martindale, Jan 3, 2004
    #8
  9. Geoff Bryant

    Skymuffins Guest

    "Tony Spadaro" <> wrote in message
    news:cYtJb.233234$...
    > Are your film shots mostly on slide film? If so do you tend to

    under-expose
    > for greater saturation, or use a high saturation film?
    > That's teh only difference I can think of.


    Polarizing filters are more effective when facing north. Perhaps your
    shooting direction is different in these two shots?

    - Harrison




    -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
    http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
    -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
     
    Skymuffins, Jan 3, 2004
    #9
  10. Geoff Bryant

    Jim Davis Guest

    Re: Re: Polarizers and digital

    On 3 Jan 2004 21:31:58 GMT, (Dave Martindale)
    wrote/replied to:

    >
    >What happens if you disable the auto white balance, then shoot with and
    >without a polarizer?


    polarized shots. no change in white balance

    you should disable your auto white balance and shoot RAW at all times

    you should get a good conversion program like Capture One
     
    Jim Davis, Jan 4, 2004
    #10
  11. Geoff Bryant

    Christian Guest

    Geoff Bryant wrote:

    > After many years shooting transparency film I made the switch to digital
    > last August. I'm more than happy with the results but one thing intrigues
    > me and perhaps someone here can enlighten me.
    >
    > Clearly cameras follow the same optical laws regardless of the capture
    > medium, but I've noticed that with digital filters seems to have less
    > effect.
    >
    > I can understand this with coloured filters that may be negated somewhat
    > by automatic white balance, but what intrigues me is how the virtual trade
    > mark effect of a polarizer - deep blue to almost black skies - seems so
    > much reduced.
    >
    > Yesterday I took some test shots with my 10D. It's midsummer here in the
    > southern hemisphere and the sky was clear blue with a just a very few pure
    > white clouds. The polarized shots certainly showed sharper contrast
    > between the clouds and the sky and the colours of the grass and other
    > foliage were brighter because of the reduced reflection. However, the
    > colour of the sky hardly changed; certainly not to the extent that I
    > observed through the viewfinder. With film it would probably have gone the
    > other way - a far greater effect.
    >
    > Is this really the case or am I missing something?



    I haven't used a polariser yet with my 10D but I will make one observation.
    If you are comparing film shots (particularly if you are using Velvia or
    some other high saturation, high contrast film) then you will likely see
    the effect much more than with the default settings on the 10D. DSLRs tend
    to produce fairly neutral images by default so try bumping up the
    saturation and contrast a little (either in-camera, in RAW processing or
    subsequent post) and then compare the results.
     
    Christian, Jan 4, 2004
    #11
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