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  1. #11

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    Sorry, Brad... I added to my post as you were replying. FWIW, I agree with you.

  2. #12
    Nicholas Lindan's Avatar
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    Quote Originally Posted by Q.G. View Post
    As if putting a filter in front of a lens magically increases the light coming off the flowers
    Yeah, that was badly phrased.

    Filters can only darken, obviously.

    But sometimes the effect is as if the object was lightened rather than the surround darkened. If you have more than two objects in the scene the distinction between lightening and darkening becomes real.

    I judge filtration by comparing the results of the filter on the object against a grey card. Something that darkens the leaves would darken them in relation to a grey card - if the leaf and card have the same relative value and placing a filter in the light path doesn't alter the relationship of the filter to the card then in my book it didn't really darken the leaves. Conversely if the flower became brighter in relation to the grey card with the filter in place I think of the filter as lightening the flower rather than darkening the grey card or the leaves.

    Lets say we have a scene of a flower, leaves and sky. In the prints the tonal value of the sky stays the same. If the relationship of the flower and the sky stays the same but the leaves go dark then I think of it as darkening the leaves because that's what it looks like in the final print. If the filter darkens the leaves and sky, passing the wavelength of the flower, then I think of it as lightening the flower - again, because that's what it looks like in the print as the exposure was increased to maintain the sky's (and in this case, the leave's) tone.

    Science Vs art; reality Vs perception. Photography is the use of science and reality to make art and alter perception.
    Last edited by Nicholas Lindan; 09-03-2009 at 03:27 PM. Click to view previous post history.
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  3. #13

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    Quote Originally Posted by BradS View Post
    only in a sophistical sort of way....
    We generally increase exposure when using contrast filters...so, of course, the red flowers do turn out lighter when photographed with a red filter.
    Ah!
    But "in a sophistical sort of way" i must argue that you only increase exposure to get the same density in the flower you would have gotten without the filter (compensate for unwanted absorbtion), while the disproportionate blocking of other colours by the filter would ensure that the foliage still has less density on the negative, despitre increased exposure.

    The red flower actually appears as light in your photo as it would have done witout the filter (unless you want to overexpose it). The green foliage will appear darker.

    Unless you add additional lights to pick out bits of your scene, and those alone, you really only darken things.
    "Really", in a non-'sophistical' way.

    It doesn't matter much, were it not that thinking in terms of lightening and darkening only makes the issue appear more complex than it actually is.
    A filter selectively blocks light. It is as simple as that.
    Though you of course can, there is no need to think about it in any other way.

    But even then, it really doesn't matter much.

  4. #14
    Martin Aislabie's Avatar
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    Thanks guys for the advice

    I used to know the colour wheel stuff but as I haven't done colour in decades it’s all gone

    I have some colour photography books in the attic gathering dust - which I cannot get to

    The suggestion of Nicholas to compare the colour though a filter against grey card is a really great idea

    Martin

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