Mark-60
Little Dog
ISO? What the heck is ISO?
I get asked this question a lot by people who are new to digital photography. Your camera has a sensor in it that allows it to capture the image. ISO is that sensors sensitivity to light. The higher the ISO number, the more sensitive to light it is. This will allow you to achieve higher shutter speeds or lower f-stops when shooting in lower light situations, E.g., indoors or at dusk or dawn. The down side to higher ISO settings is that the higher the number, the more “grain” or “noise” you get in the image.
The above image was shot at ISO 1250 with a Canon 1D Mark II (this is a fairly old tech camera these days) and a Canon 70-200 f2.8 L lens. Notice in the upper right corner where it’s kind of dark you can see “grain” or “noise” in the image very clearly. This is due to the Higher ISO number.
Newer cameras are getting better and better about getting rid of the noise at higher ISO settings. The Nikon D3x and Canon 5D Mark II are supposed to be amazing at ISO 1600 and even higher. Point and shoot cameras tend to set the ISO automatically for you as does your SLR camera if you are in “automatic mode” which none of us use, right?
The rule of thumb for setting ISO is use the lowest setting you can get away with using.
Let me give an example of when you would or should change your ISO setting. Let’s say you’re in your house shooting your dog. The lighting in your house isn’t that great so you’ve got your ISO setting high so you can get faster shutter speeds to freeze the motion, you then go outside and want to shoot your dog some more. If you leave your ISO setting at 1200 or whatever, you will get really, really fast shutter speeds but will have very noisey/grainy images. Move your ISO setting down to 100 or 200ish. Now if you go back in the house, and try to shoot your dog some more, you’ll find the shutter speed is not fast enough to freeze the action of you dog moving around. Just adjust the ISO setting as high as it takes to get the shutter speed to increase enough to freeze the action.
Does this make sense? Any questions? Does anyone else have anything to add that I may have missed?
Comments/additions are welcome.
-Mark.
I get asked this question a lot by people who are new to digital photography. Your camera has a sensor in it that allows it to capture the image. ISO is that sensors sensitivity to light. The higher the ISO number, the more sensitive to light it is. This will allow you to achieve higher shutter speeds or lower f-stops when shooting in lower light situations, E.g., indoors or at dusk or dawn. The down side to higher ISO settings is that the higher the number, the more “grain” or “noise” you get in the image.

The above image was shot at ISO 1250 with a Canon 1D Mark II (this is a fairly old tech camera these days) and a Canon 70-200 f2.8 L lens. Notice in the upper right corner where it’s kind of dark you can see “grain” or “noise” in the image very clearly. This is due to the Higher ISO number.
Newer cameras are getting better and better about getting rid of the noise at higher ISO settings. The Nikon D3x and Canon 5D Mark II are supposed to be amazing at ISO 1600 and even higher. Point and shoot cameras tend to set the ISO automatically for you as does your SLR camera if you are in “automatic mode” which none of us use, right?
The rule of thumb for setting ISO is use the lowest setting you can get away with using.
Let me give an example of when you would or should change your ISO setting. Let’s say you’re in your house shooting your dog. The lighting in your house isn’t that great so you’ve got your ISO setting high so you can get faster shutter speeds to freeze the motion, you then go outside and want to shoot your dog some more. If you leave your ISO setting at 1200 or whatever, you will get really, really fast shutter speeds but will have very noisey/grainy images. Move your ISO setting down to 100 or 200ish. Now if you go back in the house, and try to shoot your dog some more, you’ll find the shutter speed is not fast enough to freeze the action of you dog moving around. Just adjust the ISO setting as high as it takes to get the shutter speed to increase enough to freeze the action.
Does this make sense? Any questions? Does anyone else have anything to add that I may have missed?
Comments/additions are welcome.
-Mark.