ISO stands for International Organization for Standardization which isn’t terribly helpful in letting us know what it means. ISO was used to describe film “speeds” in the days of film. Films were graded by how “fast” they could expose for light. If you wanted a different ISO or speed film, you had to finish a roll and put in a new roll of film with a different ISO number.
Today in Digital photography as with most things, ISO is much easier, you (or the camera) can change it on the fly depending on conditions.
The best way to think of ISO is as the sensitivity of your camera’s sensor to light. The lower the number, the less sensitive to light your sensor is, the higher, the more sensitive.
So on a sunny day, you would want a very low ISO (most DSLRs bottom out at 100), while in a dark room, you might want a higher ISO.
How high an ISO is too high? As with most things, it depends. At very high ISOs, the camera introduces noise into the picture visible as extra dark pixels on your shot. This varies based on the camera sensor’s capability. Lower end camera’s may start to encounter noise at relatively low ISOs like 600-800, while higher end cameras may show little to no noise at much higher ISOs up to 12,500 and above.
Experimentation is the key.
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This entry was posted in Photography by Rich