How does ISO setting work?

Discussion in 'Digital SLR' started by David, Mar 5, 2010.

    Wolfgang Weisselberg, Mar 6, 2010
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  2. David

    NameHere Guest

    A good kicking? LOL!!!!!!!! I know ALL about cooling sensors for
    astronomical imaging. I use a stacked-peltier system on my own telescopes.
    Both, cooling systems and telescopes of my own design. I know all about
    noise. Like the kind that you consistently spew into discussions. I'm
    telling you that I discovered something about noise that I and others had
    not known of before. I've made quite a few original discoveries in life
    from some of the most simplest of things, this being but one of them.
    Another that was recently submitted to the Nobel Prize Committee. After
    seeing how simply they were able to make a Bose-Einstein condensate and it
    got an award, it got me to thinking that other independent discoveries that
    are just as obvious (to me) are probably equal if not more important. I now
    use what I have discovered about noise to my benefit. [I think I should
    submit the original discovery I made in order to create a tunable molecular
    sieve that I designed too. Nah, let's see how they handle the last one on
    their desk. If they don't comprehend the importance of the one submitted
    (its implications as far reaching as the survivability of humanity), then
    they don't get the discovery I made that led to my tunable molecular

    "Discovery consists of seeing what everybody has seen and thinking what
    nobody has thought." - Albert von Szent-Gyorgyi

    Remain with your head stuck up in the dark and ignorant recesses of your
    ass. It's quite entertaining!
    NameHere, Mar 6, 2010
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  3. David

    MikeWhy Guest

    Now this is really weird. My toilet overflowed last night and made a pretty
    big mess. I cleaned up the best I could, but how the hell did it get into
    the PC? Is anyone else seeing this?
    MikeWhy, Mar 6, 2010
  4. David

    David Guest

    Thank you. I don't have any problem ignoring trolls.

    Somehow I had never considered setting my Canon 30D to ISO 100.
    I had always understood noise to be a factor in poorly lit situations.
    Now I know better - lets see if I will notice the difference in my pictures.

    Dave S.
    David, Mar 6, 2010
  5. David

    Ray Fischer Guest

    Yes it does.
    Inane quibbling.
    Ray Fischer, Mar 7, 2010

  6. He's hiding from me.

    And 88% of the rest of the readers in this NG.
    John McWilliams, Mar 8, 2010
  7. Ray's confused, now attacking any one at all.
    Stick to the trolls, Ray, or keep telling the pest he's a moron, as it's
    really helping....
    John McWilliams, Mar 8, 2010
  8. David

    Ray Fischer Guest

    Says the protector of trolls.
    Ray Fischer, Mar 8, 2010
  9. David

    LOL! Guest

    OH yes, the world revolves around you. EVERYONE IS OUT TO GET YOU!

    LOL!, Mar 8, 2010
  10. Both Ray and John Sheehy are right.

    - at a given brightness [i.e. count] level in the output image, if the ISO
    is increased, less exposure is needed to reach that level, and less
    exposure means a lower signal-to-noise ratio.

    - with a given input light level and exposure [i.e. number of photons],
    increasing the ISO does not [nominally] change the signal-to-noise ratio,
    but does alter the out brightness [count].

    David J Taylor, Mar 8, 2010
  11. David

    Paul Furman Guest

    Increasing ISO for the purpose of shortening hand-holding shutter speed
    is usually detrimental unless there are not highlights to be saved, and
    you purposely overexpose, then dial down in post-processing. That last
    approach improves things as long as you don't care about highlights.

    This suggests a 2-shot HDR approach where one is overexposed with high
    ISO and one is low ISO, metered to save all highlights. Apply a little
    shake adjustment to match with a small crop and do it all in camera
    (with 2 raw files for the nitpickers).

    <awaiting royalty checks from all the big camera-makers>
    <<with due share to John S.>>




    Get on it Keeoit! chdk hacking sounds fun, and it probably will be
    routine some day to have a number of apps running on your camera.
    Paul Furman, Mar 9, 2010
  12. David

    Paul Furman Guest

    On a tripod in low light or hand held in full noon sun.
    If hand-held, when highlights are at risk of being blown.

    While you can hand hold at that focal length, keep ISO low unless you
    don't care about the highlights, then go ahead & boost the ISO (and
    overexpose) to take advantage.

    Gray duck moving across gray pond with no sky:
    -boost ISO and overexpose (then dial down in post).

    Alpine sunset at dusk with beautiful bright sky and clouds:
    (and almost all scenes with a sky or important highlights)
    -keep ISO low and use a tripod when needed.
    Paul Furman, Mar 9, 2010
  13. Too late -- the Sony A550 already does that :)
    Chris Malcolm, Mar 10, 2010
  14. David

    John A. Guest

    Pentax K7 as well.
    John A., Mar 10, 2010
  15. David

    Paul Furman Guest

    Closest Nikon has is to underexpose then lift the shadows.
    Paul Furman, Mar 10, 2010
  16. David

    MikeWhy Guest

    That's no bargain. That exposure is 4x as long as a single ISO 100 shot, not
    counting 15 additional starts and stops. (The world is divided into 10 kinds
    of people: those who get it, and those who don't.)
    MikeWhy, Mar 11, 2010
  17. David

    Ray Fischer Guest

    False conclusions like "higher ISO makes for noiser pictures"?
    You are an idiot. Would you like to know why you're an idiot?
    Ray Fischer, Mar 11, 2010
  18. David

    Ray Fischer Guest

    Wrong on both counts.

    You're an idiot because you think that it matters where the noise
    comes from. It doesn't. It matters how much noise is in the
    resulting image. Increasing ISO increases noise in the image.
    Idiotic nonsense about how the camera does introduce the noise is
    of not the slightest relevance.
    Ray Fischer, Mar 11, 2010

  19. In this case, one might see more than a tad of projection by Ray.
    John McWilliams, Mar 11, 2010
  20. David

    Ray Fischer Guest

    Go away, asshole troll.
    Ray Fischer, Mar 11, 2010
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