Neutral density filters

Discussion in 'Digital Photography' started by ronviers@gmail.com, May 27, 2009.

  1. Guest

    , May 27, 2009
    #1
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  2. Ray Fischer Guest

    <> wrote:
    >I was reading on wiki:
    >http://en.wikipedia.org/wiki/Neutral_density_filter
    >that neutral density filters are not perfect.
    >
    >Can someone give me a simple explanation for why and how they are not
    >perfect, and a brief description of how they are made?


    The article explained how they are not perfect. If you cited the
    article then you should have read it.

    --
    Ray Fischer
     
    Ray Fischer, May 27, 2009
    #2
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  3. ronviers Guest

    It just says, "they do not reduce the intensity of all wavelengths
    equally".

    In what way? What casts can be expected? When Photoshop emulates a nd
    filter, what is being changed?
    How are they not perfect?
     
    ronviers, May 27, 2009
    #3
  4. Ray Fischer Guest

    ronviers <> wrote:
    >It just says, "they do not reduce the intensity of all wavelengths
    >equally".
    >
    >In what way? What casts can be expected?


    It depends upon the particular filture and the manufacturer. Try to
    use some common sense.

    > When Photoshop emulates a nd
    >filter, what is being changed?


    Photoshop reduces the intensity. It is not a filter.

    >How are they not perfect?


    "they do not reduce the intensity of all wavelengths equally"

    --
    Ray Fischer
     
    Ray Fischer, May 27, 2009
    #4
  5. ronviers Guest

    >"It depends upon the particular filture and the manufacturer. Try to
    >use some common sense."


    In other words, you do not know.

    >"Photoshop reduces the intensity. It is not a filter."


    Using the Photoshop adjustment layer 'Black and White' there is a
    *filter* option 'Neutral Density'. It does not affect the colors
    evenly. Does the uneven distribution correspond to predictable
    imperfections from nd filters?

    >"they do not reduce the intensity of all wavelengths equally"


    In what way? What casts can be expected?
     
    ronviers, May 27, 2009
    #5
  6. Don Stauffer Guest

    wrote:
    > I was reading on wiki:
    > http://en.wikipedia.org/wiki/Neutral_density_filter
    > that neutral density filters are not perfect.
    >
    > Can someone give me a simple explanation for why and how they are not
    > perfect, and a brief description of how they are made?


    Some may not be perfectly "neutral". They may have some "color" to
    them. Also, there might be a slight transmittance variance across them.

    However, these effects are very minor. Any reputable brand of ND filter
    will give you no substantial problems. Go ahead and buy a set.

    There are two kinds. In one an absorbing substance is dissolved in the
    glass. In the other kind, generally used for VERY high attenuation, a
    thin metallic film is deposited on the surface of a clear glass.
     
    Don Stauffer, May 27, 2009
    #6
  7. Ray Fischer Guest

    ronviers <> wrote:
    >>"It depends upon the particular filture and the manufacturer. Try to
    >>use some common sense."

    >
    >In other words, you do not know.


    Quite whining because you're stupid.

    >>"Photoshop reduces the intensity. It is not a filter."

    >
    >Using the Photoshop adjustment layer 'Black and White' there is a
    >*filter* option 'Neutral Density'.


    It. Is. Not. A. Filter. It is a program which reproduces the effects
    of filters.

    > It does not affect the colors
    >evenly.


    And if you already know the answer to the question then why are you
    asking?

    > Does the uneven distribution correspond to predictable
    >imperfections from nd filters?


    "It depends upon the particular filter and the manufacturer."

    >>"they do not reduce the intensity of all wavelengths equally"

    >
    >In what way? What casts can be expected?


    "It depends upon the particular filter and the manufacturer."

    --
    Ray Fischer
     
    Ray Fischer, May 27, 2009
    #7
  8. Ray Fischer Guest

    ronviers <> wrote:
    >>"It depends upon the particular filture and the manufacturer. Try to
    >>use some common sense."

    >
    >In other words, you do not know.


    Quit whining because you're stupid.

    >>"Photoshop reduces the intensity. It is not a filter."

    >
    >Using the Photoshop adjustment layer 'Black and White' there is a
    >*filter* option 'Neutral Density'.


    It. Is. Not. A. Filter. It is a program which reproduces the effects
    of filters.

    > It does not affect the colors
    >evenly.


    And if you already know the answer to the question then why are you
    asking?

    > Does the uneven distribution correspond to predictable
    >imperfections from nd filters?


    "It depends upon the particular filter and the manufacturer."

    >>"they do not reduce the intensity of all wavelengths equally"

    >
    >In what way? What casts can be expected?


    "It depends upon the particular filter and the manufacturer."

    --
    Ray Fischer
     
    Ray Fischer, May 27, 2009
    #8
  9. SneakyP Guest

    Neil Ellwood <> wrote in
    news::

    > On Wed, 27 May 2009 00:44:57 -0700, ronviers wrote:
    >
    >>>"It depends upon the particular filture and the manufacturer. Try to
    >>>use some common sense."

    >>
    >> In other words, you do not know.

    > He does know, he wants YOU to think for yourself.
    >>
    >>>"Photoshop reduces the intensity. It is not a filter."

    >>
    >> Using the Photoshop adjustment layer 'Black and White' there is a
    >> *filter* option 'Neutral Density'. It does not affect the colors evenly.
    >> Does the uneven distribution correspond to predictable imperfections
    >> from nd filters?

    > Try it and find out.
    >>
    >>>"they do not reduce the intensity of all wavelengths equally"

    >>
    >> In what way? What casts can be expected?

    > Think - filters are made by differing manufacturers and have varying
    > characteristics.
    >
    >

    I think the OP has a neURal density filter applied to his brain.




    --
    SneakyP
    To reply: newsgroup only, what's posted in ng stays in ng.

    Some choose to swim in the potty bowl of nan-ae rather than flush it
    down :0)
     
    SneakyP, May 28, 2009
    #9
  10. SneakyP Guest

    Filter To Attenuate Reds was: Neutral density filters

    bugbear <bugbear@trim_papermule.co.uk_trim> wrote in
    news::


    > Interestingly, one could (in theory) make a close-to-perfect
    > ND filter FOR A PARTICULAR camera by using equal densities
    > of the filter materials used in the bayer matrix of the camera.
    >
    > It would not affect *all* wavelengths equally, but (of course)
    > in a three colour camera, only three wavelength (groups)
    > matter.
    >

    That would bring up an interesting matter.

    Is there a filter that will partially block the reds. I find that too much
    red will oversaturate the receptors and make it appear yellow (at least in
    my camera).


    --
    SneakyP
    To reply: newsgroup only, what's posted in ng stays in ng.

    Some choose to swim in the potty bowl of nan-ae rather than flush it
    down :0)
     
    SneakyP, May 29, 2009
    #10
  11. Peter Irwin Guest

    Re: Filter To Attenuate Reds was: Neutral density filters

    SneakyP <> wrote:
    >>

    > That would bring up an interesting matter.
    >
    > Is there a filter that will partially block the reds. I find that too much
    > red will oversaturate the receptors and make it appear yellow (at least in
    > my camera).
    >

    A cyan (minus red) CC (colour compensating) filter will partially
    block the reds. They are available in various strengths.

    Peter.
     
    Peter Irwin, May 29, 2009
    #11
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