In the last article about the exposure triangle we took an in-depth look at the shutter speed and we mentioned how sometimes it was better to use a slow shutter speed than a high ISO. Now we're going to analyze why this happens.
First of all what is the ISO setting?
The ISO setting represents the sensors sensitivity to light.
Getting into more technical details, the ISO setting in digital photography is the gain of the sensor's signal. Although we speak about digital photography the camera's sensor itself is an analog device, just like a microphone for example, and as such its signal can be amplified to get more light into the picture.
This can be useful because it will allow us to use a faster shutter speed or smaller aperture when we need it (see article about shutter speed), but amplifying the signal will create noise, which will translate into small color dots
in our image like in this example photograph. Depending on the camera and the ISO setting this noise can go from slightly visible to spoiling our image. Most modern DSLRs will be able to handle noise from ISO 200 to 800 at acceptable noise rates, but it's always a good idea to keep ISO at its minimum and only rise it when the we're forced to.
As an example a typical situation where you're forced to rise the ISO is at concert photography, where there is dim light and you can't use slow shutter speed because the subject would be blurred, in that case you can only rise the ISO, although you know you will have an image with some noticeable noise.
Summing up all you need to know about ISO is that you have to keep it as low as you can by using, when possible a slow shutter speed or a big aperture.
First of all what is the ISO setting?
The ISO setting represents the sensors sensitivity to light.
Getting into more technical details, the ISO setting in digital photography is the gain of the sensor's signal. Although we speak about digital photography the camera's sensor itself is an analog device, just like a microphone for example, and as such its signal can be amplified to get more light into the picture.
This can be useful because it will allow us to use a faster shutter speed or smaller aperture when we need it (see article about shutter speed), but amplifying the signal will create noise, which will translate into small color dots
in our image like in this example photograph. Depending on the camera and the ISO setting this noise can go from slightly visible to spoiling our image. Most modern DSLRs will be able to handle noise from ISO 200 to 800 at acceptable noise rates, but it's always a good idea to keep ISO at its minimum and only rise it when the we're forced to.As an example a typical situation where you're forced to rise the ISO is at concert photography, where there is dim light and you can't use slow shutter speed because the subject would be blurred, in that case you can only rise the ISO, although you know you will have an image with some noticeable noise.
Summing up all you need to know about ISO is that you have to keep it as low as you can by using, when possible a slow shutter speed or a big aperture.
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