ISO equivalent

Discussion in 'Digital Photography' started by Ockham's Razor, Mar 22, 2007.

  1. Can anyone please tell me how ISO values relate to either DIN or ASA
    film speed?

    Thanks

    --
    "When fascism comes to America, it will be wrapped in the flag and
    carrying a cross."
    Sinclair Lewis
    Ockham's Razor, Mar 22, 2007
    #1
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  2. Ockham's Razor

    John Bean Guest

    On Thu, 22 Mar 2007 14:57:09 -0700, Ockham's Razor
    <> wrote:

    >Can anyone please tell me how ISO values relate to either DIN or ASA
    >film speed?


    The numbers commonly used on digital cameras (eg "ISO 100")
    are the same numbers used in the old ASA scale.

    But film has also used ISO for many years, perhaps you
    haven't noticed ;-)

    --
    John Bean
    John Bean, Mar 22, 2007
    #2
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  3. Ockham's Razor

    Ken Lucke Guest

    In article
    <-sjc.supernews.net>, Ockham's
    Razor <> wrote:

    > Can anyone please tell me how ISO values relate to either DIN or ASA
    > film speed?
    >
    > Thanks


    Such things as these are easily searched for using google.

    Googled, from LuminousLandscape.com:
    A) The technical answer is that no digital camera has any true ISO
    speed: there is only an ISO standard defining film speed, based on
    things like shadow handling and contrast, and this is reported in both
    ASA Exposure Index units like 100, 125, 160, etc. and DIN degree units
    21º, 22º, 23º, etc. (Note that films always report the speed as
    something like "ISO 100/21º", combining the ASA and DIN units. Despite
    what numerous photographic books say, it is not true that the ISO
    standard simply adopted the ASA scale: they merged ASA and DIN, for the
    sake of international bureaucratic harmony.)

    There is no such ISO standard for the sensitivity of electronic sensors
    yet. (There is a "base ISO" standard for the overexposure limit of a
    sensor, but that is the opposite thing to a sensitivity measure.)

    B) The practical answer is that almost everyone (incorrectly?) refers
    to those ASA units for measuring Exposure Index by the name "ISO",
    regardless of whether a high "ISO" setting has far better or worse
    shadow handling than required of a film with that ISO speed rating.


    More from wikipedia:

    ISO film speed scales

    The standard known as ISO 5800:1987 from the International Organization
    for Standardization (ISO) defines both a linear scale and a logarithmic
    scale for measuring film speed.

    In the ISO linear scale, which corresponds to the older ASA scale,
    doubling the speed of a film (that is, halving the amount of light that
    is necessary to expose the film) implies doubling the numeric value
    that designates the film speed. In the ISO logarithmic scale, which
    corresponds to the older DIN scale, doubling the speed of a film
    implies adding 3° to the numeric value that designates the film speed.
    For example, a film rated ISO 200/24° is twice as sensitive as a film
    rated ISO 100/21°.

    Commonly, the logarithmic (DIN) component is omitted from film speed
    ratings, and only the linear component is given (e.g. "ISO 100"). In
    such cases, the quoted "ISO" rating is in effect synonymous with the
    older ASA standard.

    --
    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, Mar 22, 2007
    #3
  4. Ockham's Razor

    Dimitris M Guest

    > Can anyone please tell me how ISO values relate to either DIN or ASA
    > film speed?


    15 DIN = ISO 25
    ....
    18 DIN = ISO 50
    19 DIN = ISO 64
    20 DIN = ISO 80
    21 DIN = ISO 100
    ....
    24 DIN = ISO 200
    27 DIN = ISO 400

    etc, every 3 DIN the ISO is doubled. Or every 1 DIN, ISO is x1,26

    DIN is logarithmic scale. ISO is linear
    --
    Dimitris M
    Dimitris M, Mar 22, 2007
    #4
  5. Ockham's Razor

    Morton Guest

    Dimitris M wrote:
    >> Can anyone please tell me how ISO values relate to either DIN or ASA
    >> film speed?

    >
    > 15 DIN = ISO 25
    > ...
    > 18 DIN = ISO 50
    > 19 DIN = ISO 64
    > 20 DIN = ISO 80
    > 21 DIN = ISO 100
    > ...
    > 24 DIN = ISO 200

    Morton
    > 27 DIN = ISO 400
    >
    > etc, every 3 DIN the ISO is doubled. Or every 1 DIN, ISO is x1,26
    >
    > DIN is logarithmic scale. ISO is linear

    You can just remember that 12 DIN = 12 ISO, and that adding 3 to the DIN
    = doubling the ISO.
    Morton, Mar 23, 2007
    #5
  6. Ockham's Razor

    Cynicor Guest

    Dimitris M wrote:
    >> Can anyone please tell me how ISO values relate to either DIN or ASA
    >> film speed?

    >
    > 15 DIN = ISO 25
    > ...
    > 18 DIN = ISO 50
    > 19 DIN = ISO 64
    > 20 DIN = ISO 80
    > 21 DIN = ISO 100
    > ...
    > 24 DIN = ISO 200
    > 27 DIN = ISO 400
    >
    > etc, every 3 DIN the ISO is doubled. Or every 1 DIN, ISO is x1,26
    >
    > DIN is logarithmic scale. ISO is linear


    So if a company is ISO 9000 certified, it works in extremely low light?
    Cynicor, Mar 23, 2007
    #6
  7. David J. Littleboy, Mar 23, 2007
    #7
  8. Cynicor <> writes:

    > Dimitris M wrote:
    >>> Can anyone please tell me how ISO values relate to either DIN or ASA
    >>> film speed?

    >> 15 DIN = ISO 25
    >> ...
    >> 18 DIN = ISO 50
    >> 19 DIN = ISO 64
    >> 20 DIN = ISO 80
    >> 21 DIN = ISO 100
    >> ...
    >> 24 DIN = ISO 200
    >> 27 DIN = ISO 400
    >> etc, every 3 DIN the ISO is doubled. Or every 1 DIN, ISO is x1,26
    >> DIN is logarithmic scale. ISO is linear

    >
    > So if a company is ISO 9000 certified, it works in extremely low light?


    Yes, certification is a shady business.

    --
    Måns Rullgård
    =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?=, Mar 23, 2007
    #8
  9. Cynicor wrote:

    > So if a company is ISO 9000 certified, it works in extremely low light?


    Does seem that way sometimes, in my experience. Maybe "in the dark" is
    the right phrase, as in "it seems like they're working in the dark".
    David Dyer-Bennet, Mar 23, 2007
    #9
  10. Ockham's Razor

    J. Clarke Guest

    David Dyer-Bennet wrote:
    > Cynicor wrote:
    >
    >> So if a company is ISO 9000 certified, it works in extremely low
    >> light?

    >
    > Does seem that way sometimes, in my experience. Maybe "in the dark"
    > is the right phrase, as in "it seems like they're working in the
    > dark".


    So ISO 9000 is the official standard for mushroom management? "Keep 'em
    in the dark and feed 'em, uh, manure"?

    --
    --
    --John
    to email, dial "usenet" and validate
    (was jclarke at eye bee em dot net)
    J. Clarke, Mar 23, 2007
    #10
  11. Cynicor <> wrote:
    >
    > So if a company is ISO 9000 certified, it works in extremely low light?


    It means all of the employees are albinos.

    --
    Thomas T. Veldhouse
    Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0
    Thomas T. Veldhouse, Mar 23, 2007
    #11

  12. >
    > There is no such ISO standard for the sensitivity of electronic sensors
    > yet. (There is a "base ISO" standard for the overexposure limit of a
    > sensor, but that is the opposite thing to a sensitivity measure.)
    >


    Actually, there IS now an ISO standard on digital camera exposure
    "speed". Don't have the standards number handy, but there IS one.
    There is another on digital camera resolution, that is a good one, as
    it involves MEASURED resolution rather than theoretical one (based on
    no. of pixels).
    Don Stauffer in Minnesota, Mar 23, 2007
    #12
  13. Ockham's Razor

    ASAAR Guest

    On Thu, 22 Mar 2007 20:50:46 -0400, Cynicor wrote:

    >> DIN is logarithmic scale. ISO is linear

    >
    > So if a company is ISO 9000 certified, it works in extremely low light?


    It means either that the company doesn't want to expose its
    business practices to the bright lights of official scrutiny, or its
    CEO is a dim bulb.
    ASAAR, Mar 23, 2007
    #13
  14. Ockham's Razor

    Bandicoot Guest

    "Dimitris M" <> wrote in message
    news:1174602739.908450@athnrd02...
    > > Can anyone please tell me how ISO values relate to either DIN or ASA
    > > film speed?

    >
    > 15 DIN = ISO 25
    > ...
    > 18 DIN = ISO 50
    > 19 DIN = ISO 64
    > 20 DIN = ISO 80
    > 21 DIN = ISO 100
    > ...
    > 24 DIN = ISO 200
    > 27 DIN = ISO 400
    >
    > etc, every 3 DIN the ISO is doubled. Or every 1 DIN, ISO is x1,26
    >
    > DIN is logarithmic scale. ISO is linear


    Not quite. The DIN film speed scale is logarithmic, ASA, BSI, etc. are
    linear. The ISO film speed scale consists of both a logarthmic and a linear
    value, separated by a slash. So:

    15 DIN = 25 ASA = ISO 25/15
    16 DIN = 32 ASA = ISO 16/32
    17 DIN = 40 ASA = ISO 17/40
    18 DIN = 50 ASA = ISO 50/18
    19 DIN = 64 ASA = ISO 64/19
    20 DIN = 80 ASA = ISO 80/20
    21 DIN = 100 ASA = ISO 100/21
    22 DIN = 125 ASA = ISO 125/22
    23 DIN = 160 ASA = ISO 160/23
    24 DIN = 200 ASA = ISO 200/24
    25 DIN = 250 ASA = ISO 250/25
    26 DIN = 320 ASA = ISO 320/27
    27 DIN = 400 ASA = ISO 400/27
    Etc.

    But lots of people, camera makers included, abbreviate their ISO values to
    only the linear component, in which case "truncated ISO" = ASA.



    Peter
    Bandicoot, Mar 24, 2007
    #14
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