Introduction of ISO

It is almost impossible to take good pictures without understanding what ISO is and how it works. It is one of the basic things every photographer should be aware of.

Basically the ISO is the cameras sensitivity to light. The lower the ISO number is the less sensitive camera is to the light and opposite – higher number means camera is more sensitive to the light. This change of light sensitivity is possible, because of the cameras sensor – part of the camera, which is responsible for gathering the light and turning it into the image. When the light sensitivity is high, sensor can capture the image in lower light, but at the same tame it adds a lot of noises to the picture, so photographer needs to know, what ISO number is appropriate for each lightening.

Mostly all the pictures are taken with base ISO. That is the lowest ISO number possible in the camera. Usually it is 100 or 200. That makes pictures qualitative and reduces the noises. In normal or bright light the base ISO should be used, but in lower light photographer should change the ISO settings. Usually all the cameras have such ISO numbers as 100, 200, 400, 800, 1600, 3200, 6400. Some cameras have also higher numbers, but so high light sensitivity definitely will make the image noisy.

The higher ISO number also means that it takes less time to capture the image. For example, if ISO number is 100 it takes 1 second to capture the image, but with ISO number 200 it takes twice less time – only half a second. With ISO number 400 it would be only one fourth of a second and so on. So ISO also have a big impact of image quality, when moving objects are photographed. The higher the ISO number is, the lower impact the motion has on the image quality, but again, don’t forget that higher ISO also add more noises to the picture.

There is no magic formula for perfect ISO settings. Professional photographers with experience know what settings to use to get perfect photos. This skill comes with time and practice, but for beginners there are just some basic recommendations.

As it was mentioned before, for normal light always uses the basic ISO which is the lowest ISO number possible. Exception might be photographing moving objects, but also then use just little bit higher ISO than the basic ISO.

Higher ISO number is needed if you are shooting indoors without a flash. Depending on the amount of light in the room, you can change ISO to 400 or 800 to make a picture less blurry, but be aware that higher ISO will add some noises.

Some cameras have also auto ISO setting. Some might think that it is used only by very beginners, but that is not true. You can put some limits to this auto ISO for example from 100 to 400, so you don’t have to change it manually all the time, but also it doesn’t cross the needed limit.

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