ISO What is it

In gear, Tutorial by Bob Wild

What is ISO? It’s the level of sensitivity of your camera’s sensor to light. The lower the ISO number, the less sensitive it is while a higher ISO number increases the sensitivity. With increased sensitivity, your camera sensor can capture images in low-light environments without having to use a flash. But with higher sensitivity comes at a cost – it adds grain or more a common term noise to the images. This is more noticeable within you shadow area’s

Every camera has something called a base ISO, which is normally the lowest ISO number of the sensor that can produce the highest image quality with out adding noise to the picture, ideally, you should try to stay to the lowest ISO to get the highest image quality. However, it is not always possible when working in low-light conditions.

ISO numbers normally start at 100 or 200 and increment in value depending on your camera’s custom setting such as 1/3 or 1/2 stops, but the ISO stops are as follows 100, 200, 400, 800, 1600, 3200, 6400 and etc. The important thing to remember, is that each full stops, doubles the sensitivity of the sensor. So, ISO 200 is twice as sensitive than 100, while ISO 400 is twice as sensitive than 200. This makes ISO 400 four times more sensitive to light than ISO 100, and 1600 sixteen times more sensitive to light than ISO 100, etc…. What does it mean when a sensor is sixteen times more sensitive to light? It means that it needs sixteen times less time to capture an image.

ISO Speed Example:
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

Again I always try to stick to the lowest ISO of my camera, if there is ample light, the lowest ISO, will retain the most detail and normally have the highest image quality. But there are some cases where you may want to use low ISO in dim or dark environments you will need to mount your camera on a tripod or a flat surface. In that case, remember that your camera will most likely need more time to capture the scene and anything that is moving may end up blurry. This is not necessary a bad thing,

When should you increase your ISO when there is not enough light for the camera to be able to quickly capture an image. Example when I shoot indoors without a flash, shooting birds or sports on a cloudy day I will set my ISO to a higher number to be able to capture motion. Just remember that higher ISO setting my induce noise.

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