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Thread: ISO Sensitivity

  1. #1

    Default ISO Sensitivity

    Hi, folks, something is bothering me since day 1 when i got my D90.
    In the specification, the ISO Sensitivity states that
    ISO 200 - 3200 in 1/3, 1/2 or 1 EV steps with Lo-1 (0.3, 0.5, 0.7 and 1 EV (ISO 100 equivalent) under ISO 200), and Hi-1 (0.3, 0.5, 0.7 and 1 EV (ISO 6400 equivalent) over ISO 3200)
    what is meant by one-third, half, one EV steps ? would anyone care to elaborate. thanks in advance.

  2. #2
    Moderator Octarine's Avatar
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    Default Re: ISO Sensitivity

    EV = Exposure Value. Explained in the newbie guides.
    More to read also here in Wikipedia: https://secure.wikimedia.org/wikiped...Exposure_value
    EOS

  3. #3

    Default Re: ISO Sensitivity

    Quote Originally Posted by Octarine View Post
    EV = Exposure Value. Explained in the newbie guides.
    More to read also here in Wikipedia: https://secure.wikimedia.org/wikiped...Exposure_value
    ic tks, how come some pics indicates "1EV under 200" while others "ISO 200" , what is the diff ?

  4. #4

    Default Re: ISO Sensitivity

    Exposure (ISO, Shutter speeds, aperture) is based on a logarithmic scale, not a linear one. Every Exposure Value step (or one stop) either doubles (+1EV) or halves (-1EV) the exposure. It's essentially a base-2 log scale.
    +1/3 EV step - increase exposure by 1.26 (2^1/3)
    +1/2 EV step - increase exposure by 1.414 (2^1/2)

    Smaller steps just allow finer control of your exposure. Many (if not most) DSLRs allow you to vary the three exposure parameters in either 1/2 or 1/3 steps.

  5. #5

    Default Re: ISO Sensitivity

    Quote Originally Posted by Edwin Francis View Post
    Exposure (ISO, Shutter speeds, aperture) is based on a logarithmic scale, not a linear one. Every Exposure Value step (or one stop) either doubles (+1EV) or halves (-1EV) the exposure. It's essentially a base-2 log scale.
    +1/3 EV step - increase exposure by 1.26 (2^1/3)
    +1/2 EV step - increase exposure by 1.414 (2^1/2)

    Smaller steps just allow finer control of your exposure. Many (if not most) DSLRs allow you to vary the three exposure parameters in either 1/2 or 1/3 steps.
    ic, does this applies to WB as well ??

  6. #6
    Moderator daredevil123's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    ic, does this applies to WB as well ??
    WB is measured in kelvins... not steps or stops.

  7. #7

    Default Re: ISO Sensitivity

    Quote Originally Posted by daredevil123 View Post
    WB is measured in kelvins... not steps or stops.
    hi, daredevil, my ISO sensitivity is not set to AUTO, but fixed at ISO200.
    is it ok if some pics indicates "1EV under 200" while others "ISO 200"


    same goes to WB ==> auto,
    is it ok if some pics will indicate AUTO A1. 0 and other will not.

  8. #8

    Default Re: ISO Sensitivity

    Auto White Balance on my D90 is horrible, it just cannot cope with anything other than sunlight or flash. Everything else gets a strong color cast to it. does
    this applies to all D90 or i am just the unlucky one.
    when i shoot at orange tungsten light, WB set to auto, it will give strong orange color which my naked eye tells me otherwise.
    the pic reading indicates WB AUTO B3, M1.
    Dont know what to do now, anyone care to help.

  9. #9
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    Default Re: ISO Sensitivity

    Hmm.. why don't u try custom wb instead of leaving it in auto to get more accurate wb??
    Canon 550D | EF-S 18-55mm f/3.5-5.6IS | EF 50mm f/1.8II |
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  10. #10
    Moderator daredevil123's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    Auto White Balance on my D90 is horrible, it just cannot cope with anything other than sunlight or flash. Everything else gets a strong color cast to it. does
    this applies to all D90 or i am just the unlucky one.
    when i shoot at orange tungsten light, WB set to auto, it will give strong orange color which my naked eye tells me otherwise.
    the pic reading indicates WB AUTO B3, M1.
    Dont know what to do now, anyone care to help.
    I find D90's AWB to be quite good.

    BTW, is this D90 your first DSLR?

  11. #11
    Moderator daredevil123's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    hi, daredevil, my ISO sensitivity is not set to AUTO, but fixed at ISO200.
    is it ok if some pics indicates "1EV under 200" while others "ISO 200"


    same goes to WB ==> auto,
    is it ok if some pics will indicate AUTO A1. 0 and other will not.
    There are no magic settings. You need to change settings when the situation demands it.

    Sometimes I shoot at ISO200.

    Sometimes I turn auto ISO on, min ISO 200, min shutter speed depends on the lens used at the time. max ISO depend on the light conditions, usually on 1600.

  12. #12

    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    Auto White Balance on my D90 is horrible, it just cannot cope with anything other than sunlight or flash. Everything else gets a strong color cast to it. does
    this applies to all D90 or i am just the unlucky one.
    when i shoot at orange tungsten light, WB set to auto, it will give strong orange color which my naked eye tells me otherwise.
    the pic reading indicates WB AUTO B3, M1.
    Dont know what to do now, anyone care to help.
    Buy a gray card for WB and learn from it.

  13. #13
    Senior Member ZerocoolAstra's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    Auto White Balance on my D90 is horrible, it just cannot cope with anything other than sunlight or flash. Everything else gets a strong color cast to it. does
    this applies to all D90 or i am just the unlucky one.
    when i shoot at orange tungsten light, WB set to auto, it will give strong orange color which my naked eye tells me otherwise.
    the pic reading indicates WB AUTO B3, M1.
    Dont know what to do now, anyone care to help.
    it's ok on mine.
    Quite good accuracy.

    If you aren't satisfied with the results, either use another WB mode (eg. colour tempeture in K), or best shoot in RAW and correct in PP later.
    Exploring! :)

  14. #14
    Moderator Octarine's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by parky View Post
    when i shoot at orange tungsten light, WB set to auto, it will give strong orange color which my naked eye tells me otherwise.
    the pic reading indicates WB AUTO B3, M1.
    [GUESSING MODE]
    B3 could be Blue, 3 steps. M1 could be Magenta, 1 step
    [/GUESSING MODE]
    Blue and Magenta are base colours used for White balance adjustments.

    Anyway, do note that your naked eye and your camera 'see' differently. Human eye can overcome colour casts, the brain starts filtering such lights out or (in other words), our sensitivity towards a certain colour can get reduced. Easy to try: Look at any reddish lamp for a while and then look at normal daylight or fluorescent light. Both will appear greenish initially, then it fades back to normal. The camera will always record what is there in terms of light. There are complex algorithms trying to sense what is correct and they can fail.
    It needs neutral reference for the camera to determine the correct White Balance - provided there is only one type of colour cast. If you have tungsten light and shoot with flash (without any gel) there is no way to balance both colour temperatures. If the in-camera functions (either Auto or presets) cannot help you then it's time for a grey card or White Balance cap (e.g. Expodisc or other cheaper products). Use them to get at least close to a correct settings, do the rest at home with a profiled monitor. Also, it is not always good or necessary to achieve technically correct White Balance. We tend to perceive images with a slightly warmer WB as more pleasing, compared to a technically neutral WB.
    Last edited by Octarine; 10th November 2010 at 10:36 PM.
    EOS

  15. #15

    Default Re: ISO Sensitivity

    B4 calibration, wb set to tungsten, color way too warm.


    after White Balance fine tuning
    setting tungsten WB to 2650k , as recommend by kenrockwell
    i got the photos i want right out of your D90.



    many thanks to all esp the suggestions from ZerocoolAstra, it really helps

  16. #16
    Senior Member ZerocoolAstra's Avatar
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    Default Re: ISO Sensitivity



    glad I could be of help.

    When you set to Tungsten, the camera might have been expecting really 'warm' lighting. But as you can see from your photo, most of it is dark sky. So the camera could have then mis-calculated.
    Exploring! :)

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    Default Re: ISO Sensitivity

    seach in yuotube.... got alot there.

  18. #18
    Moderator daredevil123's Avatar
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    Default Re: ISO Sensitivity

    Quote Originally Posted by wcljack View Post
    seach in yuotube.... got alot there.
    ooooo someone trying to up their post count...

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