Understanding ISO

Discussion in 'Photography Beginners' Forum' started by Lizocain, Jun 13, 2010.

  1. Lizocain

    Lizocain TPF Noob!

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    Hello everyone!Im a newbie in photography,currently practising and learning about shutter speed/aparture/ISO/position and all the rest basics anyone has to go through..My camera,Olympus SP 560 UZ has an ISO range from 50-6400.However if i set it over 100 its getting more and more grainy..So,i cant help but wonder if the goal is as clean photos as possible why the camera has so many ISO stops?In what particular cases i would need ISO 1600/3200 for example?

    I just took some fast snapshot just to show you how much noise i get cause i wanna know if its my camera or generally ISO gives this results in any other body.

    1) ISO 50 (dont mind the composition,and ye i know its under exposed but it was the brighter i could give with lowest possible ISO)
    [​IMG]

    2) ISO 800
    [​IMG]


    3) ISO 6400
    [​IMG]


    Any help on how to use ISO is welcome,as well as all suggestions about books,tutorials on it.

    Thanks ;)
     
  2. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    Each time you raise the ISO you make the sensor more responcive to light - each time you do this ( as you've found out) will also incure an increase in the amount of noise and the overall quality of the shot will eventually degrade quite significantly once you get into the higher numbers.

    For a shot like you have above there is no reason to use high ISOs - you can setup on a tripod and use a nice low ISO and a long shutter speed,

    However lets change your picture for a bird flying and the lighting to cloudy and dimmer - now you need a fast shutter speed to avoid blur on the bird. You can use a wider aperture (smaller f number) to let more light throug the lens, but there is a limit on that and when you hit that limit all you have left is the ISO - raise it to a comfortable level and you can geta faster shutter speed that you need. Of course as you know there is a limit to how far you can take the ISO before the degradation is too strong for personal taste in a shot.
     
  3. EhJsNe

    EhJsNe TPF Noob!

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    Well sometimes you need the higher ISO when youre in darker situations, need fast shutter speeds, or have a low aperture (Either slow lens or you want the DOF)

    Usually when you need the speed you can sacrifice image quality and try to remove most of it in photoshop or something.

    Your camera deals with high ISO noise quite well, my D70 gets colored noise and it looks waayy worse at 1600 than yours does at 6400!
     
  4. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Your results are typical, and note that your camera reduces the MP to 1.2 at 6400 ISO.
     
  5. BuS_RiDeR

    BuS_RiDeR No longer a newbie, moving up!

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    I may be way off...

    But I try to keep my ISO in the 100 range (or lower) although sometimes that just isn't possible.

    In the old days of film cameras the ISO was more or less controlled by the film you used... Although I think that some cameras would allow manual setting of the ISO... I'm not sure how this affected the results...

    On a side note...

    :lol::lol::lol::lol::lol:

    Sorry to interupt the thread...
     
  6. myfotoguy

    myfotoguy TPF Noob!

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    Those don't look too bad considering they are high ISO, and as mentioned there are programs that will help reduce the noise in the image:
    Noise Ninja
    Topaz Plug-in for PhotoShop
    Noiseware

    As far as how to use it, I would recommend understanding the exposure relationship it has with shutter speed and aperture, An article series: Myfotoguy: The Exposure Triangle (Myfotoguy Series on Exposure Part 1 of 5)

    As far as a book, Understanding Exposure by Bryan Peterson (also mentioned in the article).
     
  7. white

    white TPF Noob!

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    It is another way of messing with the exposure triangle. It allows you to trick the light meter.
     
    Last edited: Jun 13, 2010
  8. j-dogg

    j-dogg TPF Noob!

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    Film controlled your ISO (called ASA in the day) and you had to set the ASA on the camera to what the film speed was.
     
  9. KmH

    KmH Helping photographers learn to fish Supporting Member

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    ASA - American Standards Association. Now known as ANSI - American National Standards Institute.

    ISO - International Standards Organization, based in France.

    Film was frequently 'pushed' and 'pulled' by choosing a different ASA setting on the camera from the ASA rating of the film inside.

    ASA ratings and ISO ratings are generally equal. Ie, ISO 100 = ASA 100.
     

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