Iso Question

Discussion in 'Photography Beginners' Forum' started by kcon1, Dec 19, 2007.

  1. kcon1

    kcon1 TPF Noob!

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    Pretty basic question but, what is the iso on your camera? and what does it do when you change it?
     
  2. JerryPH

    JerryPH No longer a newbie, moving up!

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    On a digital camera, ISO increases the sensor's sensitivity to light. Increasing it increases the overall brightness of a picture. Too much or too high of an ISO setting makes the pictures look gritty or have a lot of grain.

    For a more complete understanding of exposure, I *highly* recommend you purchase UNDERSTANDING EXPOSRE.
     
  3. antoine

    antoine TPF Noob!

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    ISO still confuses sometimes. I kind of get the idea of it hightening the sensitivity to light. But I don't like the grainy quality, and left with the option of using flash in dim light. Still practising.
     
  4. jstuedle

    jstuedle No longer a newbie, moving up!

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    Adjusting the ISO is the same as changing film speed in a film camera. It gives you a third variable to adjust for proper exposure. Shutter/aperture/ISO, all have trade-offs when setting up your camera. With ISO the trade-offs are - low ISO = best quality but slower shutter speeds or bigger aperture. Or a combo of the two. The inverse is true, highest available ISO + most noise (grain in film) faster shutter and/or smaller aperture for more depth of field.
     
  5. jstuedle

    jstuedle No longer a newbie, moving up!

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    As you progress, you may find noise reduction software something you would like to invest in. OTOH, by that time you may upgrade to faster glass or a body with lower noise at higher ISO.
     
  6. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    In 'digital' terms...turning up the ISO is turning up the gain on the electric signal from the sensor.

    The sensor records the light and turns that into an electronic signal. As far as I know, the lowest ISO setting on a camera is it's native signal strength...which gives you the cleanest image.

    When you turn up the ISO, the camera can make an exposure with less light. In order to do that, the camera amplifies the signal from the sensor.
    The problem with this is that the amplification causes distortion. This distortion is manifested as digital noise.

    So the more you turn up the ISO, the more digital noise you end up with.
     

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