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Thread: Filtering for a deep red filter

  1. #21

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    Re: Filtering for a deep red filter

    Quote Originally Posted by Alan Klein View Post
    Changing the ASA setting on the meter is chancy when you forget to change it back after the shot and you change or remove the red filter.
    Just to be slightly picky, it hasnít been ASA for decades. Itís ISO.

  2. #22
    Tin Can's Avatar
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    Dec 2011
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    Re: Filtering for a deep red filter

    Yes it is, but I prefer as I first learned ASA as they are the same

    While looking this up to be correct, I found a problem with Dentists

    Dental Radiography: Doses and Film Speed


    Quote Originally Posted by Bob Salomon View Post
    Just to be slightly picky, it hasnít been ASA for decades. Itís ISO.
    Tin Can

  3. #23
    Niels
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    Re: Filtering for a deep red filter

    From the Pentax Spotmeter manual:

    "When taking black-and-white pictures of a colored subject, you know that the areas adjacent to each other having little difference in light reflection, although different in visible colors, will not be reproduced on the film in proper contrast. In such a case, a proper filter is selected and used to properly reproduce the contrast.

    It is difficult, however, to select a proper filter to be used for that purpose. The Asahi Pentax Spotmeter helps select proper filters. Put the filter over the objective lens of the Spotmeter and read the difference in the L.L. readings.. . use different filters until the difference in the L.L. readings (contrast) of the picture areas in question will become greatest. Select that filter which gives the greatest difference in the L.L. readings to properly reproduce the contrast.

    The Spotmeter will also help correct illumination not only in color but also in black-arid-white photography. The reproducible contrast of a picture area is limited within a certain range as stated earlier. The Spotmeter readings of the various important picture areas will indicate which areas should be additionally illuminated."


    In other words, just put the filter in front of your meter.

    If you happen to disagree from experience; then compensate accordingly.
    ----
    Niels

  4. #24
    Drew Wiley
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    Re: Filtering for a deep red filter

    nitoplait - that odd advice has little or nothing to do with conventional filter factors, but about manipulating overall contrast through specific filter selection. Perhaps there was some application in black and white movie or TV studio sets where that method was hypothetically used, but I've never heard of anyone doing it in still photography where simple development changes work best.

  5. #25

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    Jun 2013
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    Re: Filtering for a deep red filter

    Also depends on film type. Some have a response falling to zero ~650nm, some ~700nm. Just like for the light meter's response, a small difference when unfiltered, a large difference when restricted to "red".
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  6. #26
    Alan Klein's Avatar
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    Re: Filtering for a deep red filter

    Quote Originally Posted by Bob Salomon View Post
    Just to be slightly picky, it hasnít been ASA for decades. Itís ISO.
    My meter is so old the settings are still tagged ASA

  7. #27
    Niels
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    Re: Filtering for a deep red filter

    Quote Originally Posted by Alan Klein View Post
    My meter is so old the settings are still tagged ASA
    Mine are DIN.
    ----
    Niels

  8. #28

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    Re: Filtering for a deep red filter

    One of my favorites is in Weston. lol

    And one of my favorite lens/shutter is in US stop.

  9. #29
    Drew Wiley
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    Re: Filtering for a deep red filter

    A couple of time mine were in twenty-something degrees Fahrenheit, when I accidentally dropped the meter is snowmelt streams.

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