What Happens?

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  • 05-28-2008, 10:51 AM
    PhotoChief
    What Happens?
    Hello:

    My name is PhotoChief. I have a new digital camera. My question is about changing ISO and what happens. ISO is like the ASA film speeds. But, you have to change film to get a higher ASA and then have to compensate for this change by changing your shutter speed or f/stop (aperture). This is not the case when you turn a knob and change the ISO in your digital camera. What happens to these factors if you change the ISO on your digital camera?

    Does changing the ISO on my camera change the other exposure parameters on my camera.

    Example: If I change the ISO what does this change do to the Auto and or Manual settings of my camera?

    If I change the ISO what does this change do to the aperture settings or shutter speed settings?

    Does changing from auto to manual change the ISO settings automatically?

    Does changing the aperture settings change the ISO settings automaticall?
  • 05-28-2008, 11:19 AM
    mwfanelli2
    Re: What Happens?
    Quote:
    Originally Posted by PhotoChief
    Hello:

    My name is PhotoChief. I have a new digital camera. My question is about changing ISO and what happens. ISO is like the ASA film speeds. But, you have to change film to get a higher ASA and then have to compensate for this change by changing your shutter speed or f/stop (aperture). This is not the case when you turn a knob and change the ISO in your digital camera. What happens to these factors if you change the ISO on your digital camera?

    Does changing the ISO on my camera change the other exposure parameters on my camera.

    Example: If I change the ISO what does this change do to the Auto and or Manual settings of my camera?

    If I change the ISO what does this change do to the aperture settings or shutter speed settings?

    Does changing from auto to manual change the ISO settings automatically?

    Does changing the aperture settings change the ISO settings automaticall?
    Well, you are showing your age calling the film speed ASA! That was kicked out in favor of ISO 25-30 years ago!

    ISO on a digital camera is just like ISO of film. With film, you have to change the roll to get a different ISO. In digital, you flip the dial.

    Higher ISO values make the film or sensor more sensitive to the incoming light. All the automatic modes take care of this. Manual mode, however, requires you to make the necessary changes. Just change the shutter speed and aperture in manual mode the same way you would do with higher ISO film.

    Digital works just like film, just better!
  • 05-28-2008, 11:41 AM
    Frog
    Re: What Happens?
    Not sure what camera you have but on my D80 I can choose auto iso or set it myself.
    I don't even know if going in auto mode would do an auto iso as I haven't used auto for a long time. I know I can choose iso settings in aperture/shutter priority and when in manual. I think it can also be changed in the P mode.
    If you go to higher iso, you can get smaller apertures and/or faster shutter speeds which is pretty much the same as film. You choose higher iso films to get that smaller aperture or faster shutter speed.
    The other result is a higher noise level,(as in film grain). The amount of noise varies from camera to camera and make to make. Until the introduction of the D300, I think Canon had Nikon beat for lack of noise at high iso but the D300 is as good or better than anything out there from what I've read.
  • 05-28-2008, 12:23 PM
    PhotoChief
    Re: What Happens?
    Quote:
    Originally Posted by mwfanelli2
    Well, you are showing your age calling the film speed ASA! That was kicked out in favor of ISO 25-30 years ago!

    ISO on a digital camera is just like ISO of film. With film, you have to change the roll to get a different ISO. In digital, you flip the dial.

    Higher ISO values make the film or sensor more sensitive to the incoming light. All the automatic modes take care of this. Manual mode, however, requires you to make the necessary changes. Just change the shutter speed and aperture in manual mode the same way you would do with higher ISO film.

    Digital works just like film, just better!
    Mr. Fanelli:

    You replied is easily understood and appreciated. But let me expand this line of thinking.

    Is there a difference between AF (Auto Focus) mode and AE (Auto Exposure) Mode? Do you have to set each of these independent of the other? When you are on AF can you also be on AE?

    When you are on AE must you set the setting for Aperture-Priority (AE) or Shutter-Priority (AE)?

    Does anyone know at what ISO setting the noise level starts on a Canon EOS 1Ds
    Mark III?

    Thanks in advance.
  • 05-28-2008, 12:42 PM
    Photo-John
    Re: What Happens?
    Quote:
    Originally Posted by PhotoChief
    Is there a difference between AF (Auto Focus) mode and AE (Auto Exposure) Mode? Do you have to set each of these independent of the other? When you are on AF can you also be on AE?
    Auto focus and auto exposure are separate functions. However, the focus point and exposure sensor may be tied together. That depends on the metering mode you're using. Btu the basic answer to your question is that the auto focus and auto exposure are unrelated.

    Quote:
    Originally Posted by PhotoChief
    When you are on AE must you set the setting for Aperture-Priority (AE) or Shutter-Priority (AE)?
    I'm not sure I understand this question. Aperture Priority and Shutter-Priority are both types of auto exposure. If you are using either of those exposure modes, you can set the shutter speed or aperture (depending on the mode). Abut I'm not exactly sure what you mean when you refer to a generic, "AE."

    Quote:
    Originally Posted by PhotoChief
    Does anyone know at what ISO setting the noise level starts on a Canon EOS 1Ds
    Mark III?
    Basically, with a 1Ds Mark III, you should almost never see noise. However, if you view any digital camera file at 100% on your computer, you can find noise. It will probably start to really be apparent at about ISO 400. However, your 1Ds Mark III files have so much resolution that unless you're printing at 20x24 inches or larger, at most ISO settings, noise will likely be undetectable.
  • 05-28-2008, 01:22 PM
    fx101
    Re: What Happens?
    Noise on a 1Ds MKIII? At 3200 you see a bit of "grain" but it looks more like film grain than the red and blue stuff you see when I shoot my D200 at 1600. Use some NR software and then sharpen and pretty much every image should be near noise free.
  • 05-28-2008, 01:41 PM
    PhotoChief
    Re: What Happens?
    Quote:
    Originally Posted by fx101
    Noise on a 1Ds MKIII? At 3200 you see a bit of "grain" but it looks more like film grain than the red and blue stuff you see when I shoot my D200 at 1600. Use some NR software and then sharpen and pretty much every image should be near noise free.
    What is "NR" softare?
  • 05-28-2008, 01:43 PM
    PhotoChief
    Re: What Happens?
    Quote:
    Originally Posted by Photo-John
    Auto focus and auto exposure are separate functions. However, the focus point and exposure sensor may be tied together. That depends on the metering mode you're using. Btu the basic answer to your question is that the auto focus and auto exposure are unrelated.


    I'm not sure I understand this question. Aperture Priority and Shutter-Priority are both types of auto exposure. If you are using either of those exposure modes, you can set the shutter speed or aperture (depending on the mode). Abut I'm not exactly sure what you mean when you refer to a generic, "AE."



    Basically, with a 1Ds Mark III, you should almost never see noise. However, if you view any digital camera file at 100% on your computer, you can find noise. It will probably start to really be apparent at about ISO 400. However, your 1Ds Mark III files have so much resolution that unless you're printing at 20x24 inches or larger, at most ISO settings, noise will likely be undetectable.
    Answer:

    I print to 40" X 60" as a "quality bench mark" for considering a photo good, medium or poor quality.

    What I am trying to determine in my tired old mind is what relationships Auto, Manual settings have to ISO settings and how Aperture Priority and Shutter Priority fit into the family of settings.
  • 05-28-2008, 02:15 PM
    SmartWombat
    Re: What Happens?
    AF and AE are separate.
    You can turn autofocus off and on (and lot more options besides) totally independent from the exposure mode.

    Yes AE has two modes, Tv or shutter priority and Av or aperture priority.
    Depending on what you're trying to do you will want to vary aperture or shutter speed and let the camera work out the other one to get the right exposure.

    I'm surprised to see the mkIII has P mode, I'd never use it. I prefer Tv, Av, or Manual.
  • 05-28-2008, 05:35 PM
    fx101
    Re: What Happens?
    Quote:
    Originally Posted by PhotoChief
    What is "NR" softare?
    NR Software is Noise Reduction Software. My preference is a plugin for Adobe Photoshop called "Noise Ninja." It will get rid of noise in your image at the expense of some sharpness. If you select only high noise areas and run these with the software you will end up with a virtually noise free image. Note that you only use this software if you have noticable noise, if not there's no point.