Do I really need to know about ISO numbers? and what are they, anyway?
October 16th 2008 03:02
Well, if you're using the automatic mode on your camera and it's a digital you probably don't need to know anything about them, so just click away, point and shoot and you'll be on your way.
However, should you be the unusual breed of photographer who prefers film, you will need to know at least a little to help you select your film and if you really want to improve your photography you should move along from auto to manual and then you really will need to know about ISO numbers. This applies to digital photographers too.
So just what is ISO.
Once upon a time, before the advent of digital cameras there was a film classification known as ASA.
This is the old name for the American Standards Association, which set the standards for the films carrying these numbers and you selected a particular film which suited your puposes.
This classification is now 'old hat' and we now have and have had for a considerable number of years the ISO number set by the International Standards Organization, particularly important since cameras went digital.
Films with lower ISO numbers are known as slow, or less sensitive to light; films with higher ISO numbers are faster, or more light-sensitive.
When using a film camera, it's pretty typical to shoot with ISO 100 or 200 film in normal daylight, and use ISO 400 film for lower-light photography.
Incidentally if you're venturing forth into the world of the manual photographer where you really do have a say in the type of image you produce YOU NEED TO READ YOUR MANUAL.
Tiresome, isn't it, but if you want to become a REAL photographer this is what you must do.
Every camera is different and although you will see similarities, it's the differences relating to your particular camera that are important.
But back to some more information on exposure.
If you set your camera for Action, Landscape, Portrait or Macro you will find that your camera automatically selects the best ISO speed setting.
Otherwise, you're on your own with "manual" and you really do need to understand ISO settings as well as a lot of other things.
Here you see an ISO increase from 100 to 3200. ISO 100-320 is best for bright outdoor condition, 400-800 is best indoors, over 800 is very tricky and pictures with a high ISO are considered 'noisy' meaning they come out looking grainy.
See what I mean?
Talking of films here is a range for those who like to use film in the camera.
The image below is by Gary Winters and he used the following combination to achieve his effect.
1/15s f/2.0 at 50.0mm iso800
He also used a Canon EOS Digital Rebel XTi for those who just love Canon.
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