Automatic iso value ?

Discussion in 'Digital Photography' started by Guest, May 25, 2005.

  1. Guest

    Guest Guest

    Dear all,

    I have a question regarding the ISO of my digital camera. The specifications
    say that it is 50-250. I took one picture at night, it was a bit dark as it
    was
    12 at night. I later loaded the picture into an exif viewer to see which
    settings
    where chosen automatically. I noticed that exposure was 2 seconds which
    is the max, and the ISO was 179. I have two question now: given this, is my
    picture under exposed or just the right amount, and the second one is if
    automatic mode can be a number such as 179, why do other cameras usually
    allow manual selection in steps of times-two i.e. 50/100/200/400/800/1600
    etc
    I mean, 179 is bigger than 100 but is smaller than 200, why is that?

    tia.
    Guest, May 25, 2005
    #1
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  2. Guest

    dylan Guest


    > I mean, 179 is bigger than 100 but is smaller than 200, why is that?


    It's just the way mathematics work.... ;o)
    dylan, May 26, 2005
    #2
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  3. Guest

    Roy Guest

    <olivia> wrote in message news:42950762$...
    > Dear all,
    >
    > I have a question regarding the ISO of my digital camera. The
    > specifications
    > say that it is 50-250. I took one picture at night, it was a bit dark as
    > it
    > was
    > 12 at night. I later loaded the picture into an exif viewer to see which
    > settings
    > where chosen automatically. I noticed that exposure was 2 seconds which
    > is the max, and the ISO was 179. I have two question now: given this, is
    > my
    > picture under exposed or just the right amount, and the second one is if
    > automatic mode can be a number such as 179, why do other cameras usually
    > allow manual selection in steps of times-two i.e. 50/100/200/400/800/1600
    > etc
    > I mean, 179 is bigger than 100 but is smaller than 200, why is that?
    >
    > tia.
    >
    >


    Hi there.

    We can not tell you if your pic was properly exposed or not. That all
    depends on the lighting conditions at the time.

    You can tell by looking at the picture.

    If it looks Ok, with as good range of colours as were actually visible, and
    with as good a range of tones from as Black to as White as were actually
    visible, then it is correct.

    If your camera was giving its maximum length of exposure time, and was
    working at its widest f number, it may THEN be programmed to START
    increasing the ISO value until it reaches correct exposure. That would
    account for the "In between" number.

    Not very specific, but that is my best guess.

    Roy G
    Roy, May 26, 2005
    #3
  4. Guest

    Guest Guest

    ???
    Guest, May 28, 2005
    #4
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