ISO question

Discussion in 'Photography Beginners' Forum' started by crowl31, Aug 22, 2008.

  1. crowl31

    crowl31 TPF Noob!

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    So i was a guest at a wedding this past weekend and the church/reception had some very low lighting.

    So i started increasing the ISO from 100 to 400 and then 800. This helped tremedously with getting more light in the picture. Granted this wasn't by my expertise this was jsut me messing around.

    Can someone explain to me how that works and what is the advantages/disadvantages of using a higher/lower iso.
     
  2. Ptyler22

    Ptyler22 TPF Noob!

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    I don't exactly know how it works but I do know one advantage is you can have faster shutter speeds, and one disadvantage is that if you have it too high the pictures will be noisy, and that's no good. Yep that's about all I know
     
  3. janetm1000

    janetm1000 TPF Noob!

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    in film photography ISO is the light sensitivity of film. so when you are shooting with film the only way to change your ISO is to change your film.

    in digital photography it's the light sensitivity of your sensor (if i remembered that correctly, lol). so with a digital SLR you can change your ISO according to needs.

    so yeah, higher ISO means higher sensitivity to light. but it also means your pictures are a bit more noisy, meaning they have more grain...
     
  4. crowl31

    crowl31 TPF Noob!

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    What ISO do most people shoot at?

    I would assume anything over 400 would be to much noise, is that a safe assumption?
     
  5. TamiyaGuy

    TamiyaGuy No longer a newbie, moving up!

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    It all depends on what their subject is. If they shoot sports, an ISO of 400 or even 800 is often used, but you should never have a "minimum" ISO sensitivity; always shoot at the lowest you can.

    Also, try and use your camera's "base ISO". Basically, this is the lowest ISO setting that your camera is designed to use. If your camera has a "lo" setting (I know the D300 does), try and avoid it unless it is necessary. This is because that "lo" and "hi" settings aren't true ISO values, so you'll lose some detail in photos (although not that much). The technical details are pretty complex plus I'm not even sure they're right :p.
     
  6. Beastt

    Beastt TPF Noob!

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    In film, ISO is a rating of how sensitive the chemicals on the film are to light. To make the film more sensitive, larger grains of silver halide are used. This makes the emulsion layer react more quickly to light, but also results in a grainy look to the images due to the larger grains of silver halide crystals.

    In a digital camera, a higher ISO increases the amplification of the electrical signal to the sensor. You can think of it like increasing the gain control on a microphone. It strengthens the signal, but part of that signal is noise. So when you increase the signal, you increase the noise as well. This increase in noise is visible in the form of graininess in the image.

    Some cameras do quite well at higher ISOs but all will exhibit some greater noise in the image so it's best to stay as low as is reasonable for the situation. If you're shooting with a Nikon D300, for example, you can probably get away with ISO 400 or even 800 with little appreciable increase in noise. Try the same thing with a Nikon D200 and you'll start to see the increased noise even before you hit ISO 400. In all cameras, higher ISO means greater noise. As long as you don't have to increase the ISO (and therefore the noise), just avoid doing so.
     
  7. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    It depends on the camera, the processing skills of the photographer, the processing resources, and the opinion of the viewer.

    Camera: Anything over ISO 400 gets very noisy with compact digital cameras, but DSLRs with larger sensors actually do pretty good at high ISOs. 35mm format DSLRs like the Canon 5D or Nikon D3 create usable photos at very high ISOs.

    Processing skills: If the photographer understands what causes/exaggerates noise they can take precautions to avoid it.

    Processing resources: Software such as Neat Image, Noise Ninja, and Noiseware do a pretty good job of reducing noise.

    Opinion of the viewer: Many of the most famous photos of all time are grainy as heck. While people tend to like clean images, if the photo is good in other ways noise/grain may be overlooked.

    I shoot at ISO 800 and 1600 often, and even occasionally ISO 3200 and 6400. I haven't had any complaints. I always go with the slowest ISO I can get away with, but if I'm shooting in the dark it's often a choice between a high ISO photo or no photo at all.

    EDIT: It also depends on how much the photo is going to be enlarged. Noise that looks horrible at 100% magnification may disappear completely in 4"x6" prints or web friendly sized files.
     
    Last edited: Aug 22, 2008
  8. photogincollege

    photogincollege TPF Noob!

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    Agreed I have some photos I took recently of a concert at 800 iso, all of them at 800, with my d200 it was pretty noisy at 100 %, but at any normal viewing size, or print it would still look great.
     

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what does iso sensitivity to 6400 mean?