Understanding ISO

by Rick Diffley on March 14, 2012

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Nikon D300… Manual mode… ISO 800

What is ISO?

ISO value is all about the amount of light needed for a correct exposure. Typically, a low ISO number of 100 or 200 is most often used on a sunny day. If you don’t have a lot of light, or need a fast shutter speed (Like, you don’t have a tripod.), increase the ISO number. This will automatically result in shooting with a faster shutter speed to get a correct exposure and help stop camera shake resulting in a blurry image. This is also great when you need a faster shutter speed for stop action sports. Understanding and using ISO is most important if you are shooting in manual mode which I always do to have more control over the camera.

ISO values can range from 100 all the way up to 3200! As always with digital photography these values can vary depending what camera model you own.

The Law of ISO

Increase the ISO number = Lower quality image produced out of your camera. Why?


It’s the “Noise”

When you get above 1600 ISO number your image will have more visible grainy quality. Still higher numbers resulted in larger grain or “noise,” which is very obvious. In the three images above you can see the fine “noise” that appears with increased ISO numbers. In short, this is not acceptable when you view the image on your computer monitor. Each camera handles higher ISO values differently. There are plugin programs for Photoshop, Photoshop Elements, and Aperture, that can help reduce this “noise.” The plug-in I use is Dfine from Nik Software.

The “Art” of Seeing (Revisited)

A quick sidebar regarding my image at the top of this article. I can’t count the number of times I’ve walked past this tropical plant and never thought about shooting a “group” shot. Just a reminder to always be open to the “Art” of seeing of what is around you. This is especially true if it is a place you often visit for photography. See my article referring to: “The ‘Art’ of Seeing.”

Finally, my shot is a reminder about how to improve your image taking by looking out for: “Repeat Patterns” to make your images stand out.

Test Your ISO

Go out and test your camera’s image quality and capacity at different ISO settings. Start with placing your camera on a tripod and shoot outside in the open shade. Start with your camera’s lowest ISO which should be 100 or 200. Increase the ISO values, for example: 100 or 200, 400, 800, 1100, 1600, 2200, 3200 and up to the maximum ISO. Notice the shutter speed changes as you increase the ISO values. From here, you can try shooting indoors in a dimly lit room.

Upload the images and check the quality. This is a good lesson to learn the safe ISO numbers your camera can produce without excessive “noise.”

Thank you for stopping by!

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