Sunday, February 28, 2010

ISO in a Nutshell.

Have you ever wondered what ISO is?  Well, after reading this post you should have a pretty good idea of how it works.

ISO has been around for a long time.  It is a abreviation for International Standards Organization.  In the old film days it meant the same thing as ASA.  ISO traditionally measures film speed.  The higher the number, the more sensitive the film was to light. So, ISO 400 is a more sensitive film than ISO 100.  Since you are probably not using film anymore,ISO is now how a reference to how sensitive your cameras light sensor is to light. Most cameras have several ISO setting ranging from 100 to 1600.  

Most of the time lower ISO's are most desirable because they give you less noise in your photograph.  However, choosing a higher ISO allows to you to use a smaller aperture or a faster shutter speed.  There are times when a higher ISO setting is useful. If you are shooting in low light or if you are shooting action shots you might want to raise your ISO settings. Also, If you are using a really long lens, such as a 500mm, it might be wise to raise your ISO setting to help avoid camera shake.  

If this is new to you it might be a good idea to do some tests.  Go out and shoot the same scene in all of the ISO setting your camera offers. This way you can get a feeling for what the different ISO settings produce.

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