How many stops do I lose to a polariser?

Discussion in 'Digital Photography' started by Justin C, Feb 1, 2007.

  1. Justin C

    Justin C Guest

    Took some pictures the other day at Beachy Head. For those not familiar,
    this is a large promontory on the south coast of England, made up mainly
    of chalk (very much like the white cliffs of Dover). It was a bright
    day, with very little cloud, and a low sun shining directly on the
    cliff. The sky was a beautiful blue which contrasted wonderfully with
    the cliff.

    When all around is chalk or sky metering is a bit of a headache! So I
    pulled out an incident light meter. I also pulled out a polariser to
    make the most of that blue sky, and make the most of it I did, I rotated
    it and got the maximum dark blue. My question is this, how many stops
    have I lost? I guessed two stops for the polariser, adjusted my exposure
    accordingly, but, from the images, it doesn't appear to have been enough.

    I've looked at the cases for my filters and there is no indication of
    how much light they are cutting. I'm sure I remember having this on my
    filter cases in the past, something like +1 or +2/3, to indicate (to
    those not using TTL metering) that exposure compensation is necessary.

    I look forward to your replies and comments on this.

    Justin.

    --
    Justin C, by the sea.
     
    Justin C, Feb 1, 2007
    #1
    1. Advertising

  2. Justin C

    Ken Lucke Guest

    In article <>, Justin
    C <> wrote:

    > Took some pictures the other day at Beachy Head. For those not familiar,
    > this is a large promontory on the south coast of England, made up mainly
    > of chalk (very much like the white cliffs of Dover). It was a bright
    > day, with very little cloud, and a low sun shining directly on the
    > cliff. The sky was a beautiful blue which contrasted wonderfully with
    > the cliff.
    >
    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.
    >
    > I've looked at the cases for my filters and there is no indication of
    > how much light they are cutting. I'm sure I remember having this on my
    > filter cases in the past, something like +1 or +2/3, to indicate (to
    > those not using TTL metering) that exposure compensation is necessary.
    >
    > I look forward to your replies and comments on this.
    >
    > Justin.


    Polarizers normally lose you 2-3 stops. Singh-Ray makes one that
    supposedly loses 2/3 [?] stop less than normal (they call it "LB" for
    "Lighter/Brighhter"), but I haven't tried it yet.

    Easy way to tell is to meter a scene, put the polarizer on and re-meter
    it.

    --
    You need only reflect that one of the best ways to get yourself a
    reputation as a dangerous citizen these days is to go about repeating
    the very phrases which our founding fathers used in the struggle for
    independence.
    -- Charles A. Beard
     
    Ken Lucke, Feb 1, 2007
    #2
    1. Advertising

  3. Justin C

    Scott W Guest

    On Feb 1, 1:42 pm, Ken Lucke <> wrote:

    > Polarizers normally lose you 2-3 stops. Singh-Ray makes one that
    > supposedly loses 2/3 [?] stop less than normal (they call it "LB" for
    > "Lighter/Brighhter"), but I haven't tried it yet.

    3 stops would be a lot of loss, 2 should be about the most you would
    ever lose, a good one
    should only lose about 1.5 stops. 1 stop would be the least a
    polarizer could lose if it were perfect.


    > Easy way to tell is to meter a scene, put the polarizer on and re-meter
    > it.

    Yup, this would tell you pretty quick, be sure to use a circular
    polarizer as linear ones can
    throw off the metering.
     
    Scott W, Feb 2, 2007
    #3
  4. Ken Lucke wrote:
    > In article <>,
    > Justin C <> wrote:
    >
    >> Took some pictures the other day at Beachy Head. For those not
    >> familiar, this is a large promontory on the south coast of England,
    >> made up mainly of chalk (very much like the white cliffs of Dover).
    >> It was a bright day, with very little cloud, and a low sun shining
    >> directly on the cliff. The sky was a beautiful blue which contrasted
    >> wonderfully with the cliff.
    >>
    >> When all around is chalk or sky metering is a bit of a headache! So I
    >> pulled out an incident light meter. I also pulled out a polariser to
    >> make the most of that blue sky, and make the most of it I did, I
    >> rotated it and got the maximum dark blue. My question is this, how
    >> many stops have I lost? I guessed two stops for the polariser,
    >> adjusted my exposure accordingly, but, from the images, it doesn't
    >> appear to have been enough.
    >>
    >> I've looked at the cases for my filters and there is no indication of
    >> how much light they are cutting. I'm sure I remember having this on
    >> my filter cases in the past, something like +1 or +2/3, to indicate
    >> (to those not using TTL metering) that exposure compensation is
    >> necessary.
    >>
    >> I look forward to your replies and comments on this.
    >>
    >> Justin.

    >
    > Polarizers normally lose you 2-3 stops. Singh-Ray makes one that
    > supposedly loses 2/3 [?] stop less than normal (they call it "LB" for
    > "Lighter/Brighhter"), but I haven't tried it yet.
    >
    > Easy way to tell is to meter a scene, put the polarizer on and
    > re-meter it.


    I will take some exception to that. If the polarizer is doing it's job,
    the two images will not be the same subject. They both will have an overall
    reduction, usually about 2 stops and parts of the polarized image will have
    additional reduction to only parts of the image. The best exposure of the
    second would likely not be the one metered assuming the original was
    correct. It would depend on exactly what you wanted the filter to do.

    Photography is an art and a science. This is one situation where the
    art is in the drivers seat and not science.

    --
    Joseph Meehan

    Dia 's Muire duit
     
    Joseph Meehan, Feb 2, 2007
    #4
  5. Justin C wrote:

    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.


    This is rec.photo.digital. Chimp a little! Check the histogram on a
    test exposure, and you'll know you're getting it right.

    The filter factor varies between sources and between polarizers (and
    linears seem to be different from circular), that I can find, but it
    seems to be between 2 and 3.
     
    David Dyer-Bennet, Feb 2, 2007
    #5
  6. Justin C

    Bob Williams Guest

    Justin C wrote:
    > Took some pictures the other day at Beachy Head. For those not familiar,
    > this is a large promontory on the south coast of England, made up mainly
    > of chalk (very much like the white cliffs of Dover). It was a bright
    > day, with very little cloud, and a low sun shining directly on the
    > cliff. The sky was a beautiful blue which contrasted wonderfully with
    > the cliff.
    >
    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.
    >
    > I've looked at the cases for my filters and there is no indication of
    > how much light they are cutting. I'm sure I remember having this on my
    > filter cases in the past, something like +1 or +2/3, to indicate (to
    > those not using TTL metering) that exposure compensation is necessary.
    >
    > I look forward to your replies and comments on this.
    >
    > Justin.
    >


    I depends on the scene and your position relative to the sun etc.
    I would think that you would lose about 1.5 stops just for the polarizer
    itself even if there was essentially no polarized light to be filtered.
    If you are receiving a LOT of polarized light from the sky you might
    lose another 1.5 stops.
    Perhaps you could place the polarizer over the incident light meter's
    sensor and adjust it for minimum and maximum effect.
    That would give you the f-stop loss for the filter alone and for the
    filter blocking polarized light.
    Bob Williams
     
    Bob Williams, Feb 2, 2007
    #6
  7. Justin C

    Guest

    On Feb 1, 10:37 pm, Justin C <> wrote:
    > Took some pictures the other day at Beachy Head. For those not familiar,
    > this is a large promontory on the south coast of England, made up mainly
    > of chalk (very much like the white cliffs of Dover). It was a bright
    > day, with very little cloud, and a low sun shining directly on the
    > cliff. The sky was a beautiful blue which contrasted wonderfully with
    > the cliff.
    >
    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.
    >
    > I've looked at the cases for my filters and there is no indication of
    > how much light they are cutting. I'm sure I remember having this on my
    > filter cases in the past, something like +1 or +2/3, to indicate (to
    > those not using TTL metering) that exposure compensation is necessary.
    >
    > I look forward to your replies and comments on this.
    >
    > Justin.
    >
    > --
    > Justin C, by the sea.


    yeah its usually 1.5 - 3 stops depending on how much light is
    available etc..... bracketing would be the best idea
     
    , Feb 2, 2007
    #7
  8. David Dyer-Bennet wrote:
    > Justin C wrote:
    >
    >> When all around is chalk or sky metering is a bit of a headache! So I
    >> pulled out an incident light meter. I also pulled out a polariser to
    >> make the most of that blue sky, and make the most of it I did, I
    >> rotated it and got the maximum dark blue. My question is this, how
    >> many stops have I lost? I guessed two stops for the polariser,
    >> adjusted my exposure accordingly, but, from the images, it doesn't
    >> appear to have been enough.

    >
    > This is rec.photo.digital. Chimp a little! Check the histogram on a
    > test exposure, and you'll know you're getting it right.


    I disagree. A "proper" histogram does not mean the right exposure.
    Only the resulting image can be the real test. If the results are right,
    then the exposure is right.



    >
    > The filter factor varies between sources and between polarizers (and
    > linears seem to be different from circular), that I can find, but it
    > seems to be between 2 and 3.


    --
    Joseph Meehan

    Dia 's Muire duit
     
    Joseph Meehan, Feb 2, 2007
    #8
  9. Justin C

    SimonLW Guest

    "Justin C" <> wrote in message
    news:...
    >
    > Took some pictures the other day at Beachy Head. For those not familiar,
    > this is a large promontory on the south coast of England, made up mainly
    > of chalk (very much like the white cliffs of Dover). It was a bright
    > day, with very little cloud, and a low sun shining directly on the
    > cliff. The sky was a beautiful blue which contrasted wonderfully with
    > the cliff.
    >
    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.
    >
    > I've looked at the cases for my filters and there is no indication of
    > how much light they are cutting. I'm sure I remember having this on my
    > filter cases in the past, something like +1 or +2/3, to indicate (to
    > those not using TTL metering) that exposure compensation is necessary.
    >
    > I look forward to your replies and comments on this.
    >
    > Justin.
    >
    > --
    > Justin C, by the sea.


    Depends on the incoming polarization of the light. It could pass nearly all
    the light or block it. If the light is not polarized (random) you lose
    around 2 stops. Because in reality, a scene contains a mix, it is best to
    bracket or as said, "chimp".

    While we're at it, I was at a Meijers (sp?) store and found these circular
    polarizers for $12 each in 52 and 58mm thread. These are "Targus" brand. My
    local camera shop wants $35 for a "promaster", so I figured I have nothing
    to lose (besides 24 bucks). I tested them out and they are polarizers and do
    contain the 1/4 wave plate. They work well.

    They don't come with any sort of case and claim to be "multi coated".
    There's no coating I can see.
    -S
     
    SimonLW, Feb 2, 2007
    #9
  10. Justin C

    Ron Baird Guest

    Greetings Justin,

    I believe you guessed correctly at the Polarizer. Actually, I believe it is
    about 2.3 stops. But you likely did not account for the general brightness
    of the scene, i.e. water white cliffs and blue sky. Kinda like a beach or
    other bright scene. When in that situation it is wise to increase exposure a
    bit to account for the unusual brightness. Again, about two stops if really
    bright.

    The meter in the camera will try to make the scene an 18% reflectance
    instead of the bright scene that you saw. This happens on most general use
    cameras.

    The nice thing about digital, however, is that you can run a series of shots
    to be sure you are getting the right image.

    Talk to you soon,

    Ron Baird
    Eastman Kodak Company




    "Justin C" <> wrote in message
    news:...
    >
    > Took some pictures the other day at Beachy Head. For those not familiar,
    > this is a large promontory on the south coast of England, made up mainly
    > of chalk (very much like the white cliffs of Dover). It was a bright
    > day, with very little cloud, and a low sun shining directly on the
    > cliff. The sky was a beautiful blue which contrasted wonderfully with
    > the cliff.
    >
    > When all around is chalk or sky metering is a bit of a headache! So I
    > pulled out an incident light meter. I also pulled out a polariser to
    > make the most of that blue sky, and make the most of it I did, I rotated
    > it and got the maximum dark blue. My question is this, how many stops
    > have I lost? I guessed two stops for the polariser, adjusted my exposure
    > accordingly, but, from the images, it doesn't appear to have been enough.
    >
    > I've looked at the cases for my filters and there is no indication of
    > how much light they are cutting. I'm sure I remember having this on my
    > filter cases in the past, something like +1 or +2/3, to indicate (to
    > those not using TTL metering) that exposure compensation is necessary.
    >
    > I look forward to your replies and comments on this.
    >
    > Justin.
    >
    > --
    > Justin C, by the sea.
     
    Ron Baird, Feb 9, 2007
    #10
  11. Justin C

    Justin C Guest

    On 2007-02-09, Ron Baird <> wrote:
    > Greetings Justin,
    >

    Greetings to you too.

    > I believe you guessed correctly at the Polarizer. Actually, I believe it is
    > about 2.3 stops. But you likely did not account for the general brightness
    > of the scene, i.e. water white cliffs and blue sky. Kinda like a beach or
    > other bright scene. When in that situation it is wise to increase exposure a
    > bit to account for the unusual brightness. Again, about two stops if really
    > bright.


    What part of "incident light reading" don't you understand?


    > The meter in the camera will try to make the scene an 18% reflectance
    > instead of the bright scene that you saw. This happens on most general use
    > cameras.


    What meter in what camera? I completely ignored it.


    > Talk to you soon,


    Hmmm.


    > Ron Baird
    > Eastman Kodak Company


    They let you post to a newsgroup with their name attached? *And* you
    breach netiqette by top posting! I'm sorry, but Kodak is losing
    credibility with me by letting this out the door.

    Justin.

    --
    Justin C, by the sea.
     
    Justin C, Feb 11, 2007
    #11
  12. Justin C

    John Bean Guest

    Justin, in your original post you said:

    "I look forward to your replies and comments on this"

    yet you seem to have ignored them all except Ron - at whom
    you hurl vitriol.

    It doesn't matter to me, maybe it doesn't to you either, but
    your attitude needs some work if you expect anyone to take
    you seriously.

    --
    John Bean
     
    John Bean, Feb 11, 2007
    #12
  13. Justin C

    Justin C Guest

    On 2007-02-11, John Bean <> wrote:
    > Justin, in your original post you said:
    >
    > "I look forward to your replies and comments on this"
    >
    > yet you seem to have ignored them all except Ron - at whom
    > you hurl vitriol.


    I didn't ignore them. It is unfortunate that retention on my news-server
    is such that they have expired (I've been away since last Saturday at a
    trade show) and spent much of the prior week preparing. I've caught up
    with them on Google but I'm not signing up to Google to post replies,
    I'll tack them on the end here.

    I think "vitriol" is rather strong. Ron purports to post from Kodak, a
    highly respected company in the photography industry, one without which
    the whole industry would be in very different shape. It was they who
    opened it up to the masses and I am grateful for that - I still have a
    Kodak Retina camera, which I love dearly but, alas don't use due to the
    processing costs. When posting from such an august position one should
    take the utmost care in what one writes, I doubt any advert ever leaves
    the company without very much scrutiny, of the facts, details, and
    comparison with corporate image documents; yet Ron posted a message
    which missed the point, and was poorly presented, not useing established
    usenet posting style - editing the original and inserting his post after
    the relevant part of the original. If Kodak is accepting of this
    slap-dash approach it tells me that their standards are not high enough
    to hold them in the high regard I have done any longer.


    > It doesn't matter to me, maybe it doesn't to you either, but
    > your attitude needs some work if you expect anyone to take
    > you seriously.


    People do take me seriously, just not here. :)


    With regard to the other follow-ups to my original, I think Ken Lucke
    hit the most simple solution. Though I am using an incident meter, using
    the camera's own meter with and without the polariser will show the
    difference which I can then apply to the reading from the incident
    meter. I shall keep this in mind for next time.

    Scott W, fortunately mine is a circular polariser. I bought it some
    years ago for an EOS, I recall reading that linear polarisers caused
    problems with the autofocus method used at that time.

    Thanks to those others who also replied, some interesting points were
    raised. I now know how to deal with this situation when it arises again
    - as it will, I enjoy the walk around Beachy Head and shall be there
    again before long.

    Justin.

    --
    Justin C, by the sea.
     
    Justin C, Feb 11, 2007
    #13
  14. Justin C <> wrote:
    >With regard to the other follow-ups to my original, I think Ken Lucke
    >hit the most simple solution. Though I am using an incident meter, using
    >the camera's own meter with and without the polariser will show the
    >difference which I can then apply to the reading from the incident
    >meter. I shall keep this in mind for next time.


    David Dyer-Bennet gave you the correct answer. Use the camera's
    digital facilities to tell you what the exposure actually is.
    By making sure the right side of the histogram approaches the
    end of the graph you will guarantee maximum dynamic range
    without blowing the highlights.

    Of course, that assumes there are no highlights you don't mind
    blowing, which there might actually be. If so, with a
    blink-on-overexposure LCD display you can also determine exactly
    what is overexposed, so that would perhaps be even better than
    just the histogram. (As David mentioned, this is standard
    procedure for beach scenes, snow scenes, or any example where
    the average is not going to be about 18% grey.)

    I agree with the basic idea of ignoring the light meter... except
    that I'd add ignoring the external incident light meter too.

    --
    Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
    Ukpeagvik (Barrow, Alaska)
     
    Floyd L. Davidson, Feb 11, 2007
    #14
  15. Justin C

    Justin C Guest

    On 2007-02-11, Floyd L. Davidson <> wrote:
    > Justin C <> wrote:
    >>With regard to the other follow-ups to my original, I think Ken Lucke
    >>hit the most simple solution. Though I am using an incident meter, using
    >>the camera's own meter with and without the polariser will show the
    >>difference which I can then apply to the reading from the incident
    >>meter. I shall keep this in mind for next time.

    >
    > David Dyer-Bennet gave you the correct answer. Use the camera's
    > digital facilities to tell you what the exposure actually is.
    > By making sure the right side of the histogram approaches the
    > end of the graph you will guarantee maximum dynamic range
    > without blowing the highlights.
    >
    > Of course, that assumes there are no highlights you don't mind
    > blowing, which there might actually be. If so, with a
    > blink-on-overexposure LCD display you can also determine exactly
    > what is overexposed, so that would perhaps be even better than
    > just the histogram. (As David mentioned, this is standard
    > procedure for beach scenes, snow scenes, or any example where
    > the average is not going to be about 18% grey.)
    >
    > I agree with the basic idea of ignoring the light meter... except
    > that I'd add ignoring the external incident light meter too.


    I can see your point. Noted for future reference.

    Justin.

    --
    Justin C, by the sea.
     
    Justin C, Feb 12, 2007
    #15
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. jslevin

    Hoya polariser question

    jslevin, Jun 29, 2005, in forum: Digital Photography
    Replies:
    5
    Views:
    401
    Theodore Morton
    Jun 30, 2005
  2. russell

    Polariser lens for Canon S2 IS

    russell, Aug 31, 2005, in forum: Digital Photography
    Replies:
    2
    Views:
    307
    russell
    Aug 31, 2005
  3. Alfred Molon

    Why do polariser filters take away two stops of light?

    Alfred Molon, Aug 18, 2006, in forum: Digital Photography
    Replies:
    7
    Views:
    459
    Bob Salomon
    Aug 18, 2006
  4. Lawrence D'Oliveiro

    You lose some, and then you lose some ...

    Lawrence D'Oliveiro, Sep 22, 2006, in forum: NZ Computing
    Replies:
    13
    Views:
    608
    Earl Grey
    Sep 24, 2006
  5. ransley

    polariser filter

    ransley, Oct 18, 2009, in forum: Digital Photography
    Replies:
    6
    Views:
    348
    ransley
    Oct 19, 2009
Loading...

Share This Page