Sunday, September 1, 2013

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ISO Explained in Very Simple Terms + Tips

ISO (short for International Standards Organization) is the level of sensitivity of your camera to available light. The lower the ISO number, the less sensitive it is to the light, while a higher ISO number increases the sensitivity of your camera.

The part inside your camera that can change sensitivity is called “sensor”. When increased, your camera sensor can capture images in low-light environments without having to use a flash. But higher sensitivity comes at an expense – it adds grain or “noise” to the pictures. A lower ISO will usually produce more colour-accurate, aesthetically pleasing images. (compare images below)

“Base ISO“ of most cameras is 100 and some are set at 200. If you are not a professional just keep it unchanged. However if you need to change it, you will notice that its value increase in geometric progression (100, 200, 400, 800, 1600, 3200, 6400 etc.). So, each step effectively doubles the sensitivity of the sensor.
If you’re in low light conditions such as indoors or a night club, then you might need to increase your ISO to maybe 800 or 1600. When a sensor is eight times more sensitive to light, it means that it needs eight times less time to capture an image.

ISO 100 – 1 second
ISO 200 – 1/2 of a second
ISO 400 – 1/4 of a second
ISO 800 – 1/8 of a second
ISO 1600 – 1/16 of a second
ISO 3200 – 1/32 of a second

Thus by simply switching to ISO 800, you can capture the same scene at 1/8th of a second or at 125 milliseconds! This is a big help when you want to capture a motion in picture or in low light environment.

The example below shows that if your location is too dark, then by increasing your ISO you increase the light let into the lens.


  1. The higher the ISO, the noisier or “grainier” the image. 
  2. If the subject is moving, you’ll likely need a higher ISO. 
  3. For a vintage effect, don’t be afraid to bump up the ISO a few notches
  4. When using a tripod, you are allowed to use a lower ISO
  5. If shooting a ratehr close-up-ish image, you'd better increase the camera’s aperture and use a lower ISO
  6. When shooting with artificial light (i.e., using a flash), a lower ISO setting is OK
  7. Never trust your camera’s display. Don’t assume that your picture will turn out just because the tiny 2-inch preview looks adequate. Seemingly great shots might appear noisy and speckled when you upload them to your PC. 
The following images will give you a better idea how pictures look like when captured with different ISO settings.