Here is a nice little explanation of ISO by dpreview.com which is a nice source for camera reviews.
Here is a great write up about ISO by Nikon.
PART I
You are to take the same photo using all the ISOs that your camera offers. You can go by full stops; you don’t have to include fractions stops. So, it is likely that you camera’s native ISO is either 100 or 200. Start there. Determine the correct exposure. You need to change your shutter speed and aperture each time you change your ISO. For example, let's say you start with f5.6 @ 1/125 using ISO 100. When you change the ISO to 200, the camera only requires 1/2 the amount of light so you must either change your aperture to f8 or change your shutter speed to 1/250. Your exposures must be reciprocal (they should all be the same in terms of brightness). As such, the histograms should be nearly identical for all the shots. When viewed small, you shouldn’t be able to see any differences between the shots.
It will be easiest to achieve this outside on a nice day, but you can do it inside or with low light levels outside if necessary. In low light, you may have to use a slow shutter that will necessitate the use of tripod or putting the camera on something solid and releasing the shutter using the self timer. Whatever you shoot, make sure there is a variety of color and tone in the scene.
Since most of you will have a subset of the following ISOs, you should be able to complete this with less than 8 shots total.
50
100
200
400
800
1600
3200
6400
PART II
I then want you to zoom into the resulting images either on your camera, on Flickr, or using Bridge. If you zoom into 100 or 200% you should see considerable difference between the shots taken with a low ISO and those taken with a high ISO. Often, there isn’t considerable difference between the lowest few ISOs, but at some point there is a big decline in image quality. Is there a particular tonal range that you find the noise most prevalent? Describe the characteristic of the noise. At what ISO do you feel that the image becomes unacceptable? Please write your responses to these questions and your observations on ISO in the description of your highest ISO image on Flickr.
Here is a great write up about ISO by Nikon.
PART I
You are to take the same photo using all the ISOs that your camera offers. You can go by full stops; you don’t have to include fractions stops. So, it is likely that you camera’s native ISO is either 100 or 200. Start there. Determine the correct exposure. You need to change your shutter speed and aperture each time you change your ISO. For example, let's say you start with f5.6 @ 1/125 using ISO 100. When you change the ISO to 200, the camera only requires 1/2 the amount of light so you must either change your aperture to f8 or change your shutter speed to 1/250. Your exposures must be reciprocal (they should all be the same in terms of brightness). As such, the histograms should be nearly identical for all the shots. When viewed small, you shouldn’t be able to see any differences between the shots.
It will be easiest to achieve this outside on a nice day, but you can do it inside or with low light levels outside if necessary. In low light, you may have to use a slow shutter that will necessitate the use of tripod or putting the camera on something solid and releasing the shutter using the self timer. Whatever you shoot, make sure there is a variety of color and tone in the scene.
Since most of you will have a subset of the following ISOs, you should be able to complete this with less than 8 shots total.
50
100
200
400
800
1600
3200
6400
PART II
I then want you to zoom into the resulting images either on your camera, on Flickr, or using Bridge. If you zoom into 100 or 200% you should see considerable difference between the shots taken with a low ISO and those taken with a high ISO. Often, there isn’t considerable difference between the lowest few ISOs, but at some point there is a big decline in image quality. Is there a particular tonal range that you find the noise most prevalent? Describe the characteristic of the noise. At what ISO do you feel that the image becomes unacceptable? Please write your responses to these questions and your observations on ISO in the description of your highest ISO image on Flickr.
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