A&P could someone explain ISO to me in idiot terms

Discussion in 'Lifestyle' started by rob, Feb 7, 2004.

  1. rob

    rob Guest

    like ISO 50, 200, ETC .. If I were to take two pics with same settings and only change ISO, what would the end result be? I don't understand waht it is..
     
  2. BLKDVLGSX

    BLKDVLGSX OT Supporter

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    to make it simple....different digital versions of 35mm film speed I.E. 400 or 800 speed film
     
  3. Merli

    Merli gplus.to/merli OT Supporter

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    The higher the ISO number, the more sensitive to light the film is, and the less time it needs to capture the frame. This is why film that's rated ISO 400 is said to be "faster" than that of ISO 100.

    The larger the ISO number, the larger the size of the silver-halide (I think?) crystals are, and the more sensitive to light they are. So why not use faster ISO film/setting on your camera all the time and use faster shutter speed? Because the higher the ISO, the larger the crystals, and the grainier the resulting photos are, which limits the amount you can enlarge them when printing whilst still keeping good resolution...

    For digital cameras, the ISO is basically the same principle in EFFECT, but it's actually how much amplification the camera puts on the CCD sensor output before converting it to binary data. The trade off with digital cameras isn't a grainier film, instead the result is increased "noise" or "artifacts" in the frame.

    To answer your question, if you took two photos exactly the same, one at ISO 100 and one at ISO 200, that's the same as giving the camera one stop more light, exactly the same as increasing aperture one stop or increasing shutter one stop. It'll just expose the photo one stop more. Take two photos, one at ISO 100 and one at ISO 400, and that's TWO stops more light...

    Hope that helps...
     
  4. TypeSDragoon

    TypeSDragoon Guest

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