Understanding ISO

Simple guide to ISO

“In very basic terms, ISO 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 component within your camera that can change sensitivity is called “image sensor” or simply “sensor”.”

On Tuesday, we started to learn more about ISO and exposure. We did an exercise in the dark room to see how everyone’s camera and ISO coped in such low lighting. The highest ISO setting on my camera is 1600, and usually my images turn really grainy when on that setting. I was therefore pleasantly surprised to find that my images weren’t too noisy.

The left image was taken with an ISO of 800 and a shutter speed of 1/6th a second. That’s why its so dark. In contrast, the right image was taken with an ISO of 100 but with a shutter speed of 1/15th a second. However there were fluorescent lights on in the second image which improved the brightness of the image.

The image on the left is taken using an ISO of 1000 and a shutter speed of 1/15th a second. Although this image isn’t sharp, the point of the exercise was to find noise in the image. When I zoom in, you can see the noise on the person in the backgrounds arm in particular.

For the top image, I used an ISO of 1600 and a shutter speed of 13/10th second. I also moved the camera because I used a slightly longer exposure. As well as that, I used a flash which created the hot spot on the subjects nose. The movement created motion blur within the image, I really like the effect it gave the image. The second image was taken using the same technique, ISO and shutter speed.


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