Easy Basic Photography
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What is ISO in Digital Cameras?..and when to change an ISO setting
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This tutorial will explain what ISO is and how to use the ISO setting function in your digital camera.
The ISO rating or number is an indicator of how sensitive a camera's image sensor is to light at a given ISO
setting. In a digital camera, changing the ISO setting will amplify or decrease the image sensors' ability to read
light during an exposure.
ISO is an abbreviation for the International Standards Organization which set standard ratings for film sensitivity
to light. With the development of digital cameras, standards have been applied to the light sensitivity of camera
image sensors. Although the letters ISO are an abbreviation for an organization, in digital photography, they are
commonly used with a number to indicate image sensor sensitivity. See the ISO chart below.
Using a lower ISO setting such as ISO 100 will require more light to obtain a proper exposure than using a
setting of ISO 400 for the same shot. That is assuming all other factors such as the camera lens aperture
setting, the shutter speed setting, as well as the lens type remains the same.
Some of the most common ISO settings or ISO ratings are the following:
The ISO setting, shutter speed, and aperture setting are all part of what is known in photography as the
"Exposure Triangle". These three things work together to produce a "properly" exposed image. If you are not
familiar with the functions of the camera lens aperture, or the camera shutter, you might want to check the
tutorial on Camera Exposure Basics.
A basic compact camera like the FujiFilm Finepix Z700EXR has an ISO rating range from ISO 100 to ISO 1600.
The Canon EOS Rebel T2i is a Digital SLR camera that has a range from ISO 100 to ISO 6400 that can be
expandable to ISO 12800.
If you are a photographer who will be taking a lot of pictures in a low light situations without flash, then a camera
with a higher maximum ISO rating might be something to consider when thinking of purchasing a camera.
When you use your camera in the automatic mode, the ISO number will be automatically set for you. When you
use your camera in a manual or semi automatic mode, you will be able to set the ISO number yourself. However,
some very basic compact cameras do not allow you to manually change the ISO setting. It will be set
automatically depending on the scene you are photographing.
When should the ISO setting be changed? A simple example would be when you are in a dimly lit area and
it is not possible to use the camera flash. Lets assume you cannot get a properly exposed picture, (the picture
is too dark) and the camera is set on ISO 100. No problem! Try changing to a higher camera ISO setting like
ISO 400, ISO 800, or which ever ISO setting will allow you to get that properly exposed picture. Using higher ISO
setting numbers makes the image sensor more sensitive to light. Therefore, less light is needed will be needed
to obtain a properly exposed picture.
Next is an example if you are using a Digital Slr in its manual mode. Lets say you are trying to shoot a fast
moving subject. Your camera is set on ISO 100. According to your cameras' exposure meter, in order to obtain a
proper exposure, you must set your aperture to its maximum opening, (lets just use F3,5) and use a shutter
speed of 1/60. However, the shutter speed 1/60 might not be fast enough to "freeze" the action. (moving
subjects might be blurred in an image when you are using slower shutter speeds).
Change your camera setting from ISO 100 to ISO 200. That will decrease the amount of light the camera image
sensor will need for a good exposure. You will then be able to increase your shutter speed from 1/60 to 1/125
to get a properly exposed image. If that shutter speed isn't fast enough, change from ISO 200 to ISO 400. Then
increase the shutter speed to 1/250. (this example assumes the shutter speed of 1/250 was fast enough to
"freeze" the action). You will then have a nicely exposed image without any blur in it.
Lower ISO numbers are better. While it is a great thing to be able to increase your camera's ISO rating in
order to get the shot you want, there is a down side to doing it. The down side is called "digital camera noise".
The higher your ISO setting, the more noise you will see in your picture. Noise is tiny dots or specks in the
image that are generated when the sensor sensitivity is amplified in order to read more light.
Picture #1 taken at IS0 1600 Picture #2 taken at ISO 100
Picture #1 was taken with a setting of ISO 100. Picture #2 was taken with an ISO setting of 1600. You can see
that the picture taken with the ISO setting of 100 is much clearer than the picture with the ISO 1600 setting.
(click either picture to enlarge)
There is always a little noise in a photographic image, but the noise might not be visible unless the image is
greatly enlarged or the ISO setting is set to a pretty high number. Also, digital camera noise will be more visible
in darker areas of the image.
The amount of noise in an image will also vary depending on the image sensor size and make of the camera.
Digital Single Lens Reflex cameras, because of their larger sensor size will exhibit less noise than Digital
Compact cameras at higher ISO settings. In any case, getting the shot with some noise in the picture is better
than no picture at all.
Hopefully, this tutorial has clearly answered the question what is ISO? and how to use it in your digital camera. If
you need more of an explanation of how the camera aperture, camera shutter, and ISO work together to
produce "properly" exposed pictures, check the tutorial, Camera Exposure Basics
,
This tutorial will explain what ISO is and how to use the ISO setting function in your digital camera.
The ISO rating or number is an indicator of how sensitive a camera's image sensor is to light at a given ISO
setting. In a digital camera, changing the ISO setting will amplify or decrease the image sensors' ability to read
light during an exposure.
ISO is an abbreviation for the International Standards Organization which set standard ratings for film sensitivity
to light. With the development of digital cameras, standards have been applied to the light sensitivity of camera
image sensors. Although the letters ISO are an abbreviation for an organization, in digital photography, they are
commonly used with a number to indicate image sensor sensitivity. See the ISO chart below.
Using a lower ISO setting such as ISO 100 will require more light to obtain a proper exposure than using a
setting of ISO 400 for the same shot. That is assuming all other factors such as the camera lens aperture
setting, the shutter speed setting, as well as the lens type remains the same.
Some of the most common ISO settings or ISO ratings are the following:
The ISO setting, shutter speed, and aperture setting are all part of what is known in photography as the
"Exposure Triangle". These three things work together to produce a "properly" exposed image. If you are not
familiar with the functions of the camera lens aperture, or the camera shutter, you might want to check the
tutorial on Camera Exposure Basics.
A basic compact camera like the FujiFilm Finepix Z700EXR has an ISO rating range from ISO 100 to ISO 1600.
The Canon EOS Rebel T2i is a Digital SLR camera that has a range from ISO 100 to ISO 6400 that can be
expandable to ISO 12800.
If you are a photographer who will be taking a lot of pictures in a low light situations without flash, then a camera
with a higher maximum ISO rating might be something to consider when thinking of purchasing a camera.
When you use your camera in the automatic mode, the ISO number will be automatically set for you. When you
use your camera in a manual or semi automatic mode, you will be able to set the ISO number yourself. However,
some very basic compact cameras do not allow you to manually change the ISO setting. It will be set
automatically depending on the scene you are photographing.
When should the ISO setting be changed? A simple example would be when you are in a dimly lit area and
it is not possible to use the camera flash. Lets assume you cannot get a properly exposed picture, (the picture
is too dark) and the camera is set on ISO 100. No problem! Try changing to a higher camera ISO setting like
ISO 400, ISO 800, or which ever ISO setting will allow you to get that properly exposed picture. Using higher ISO
setting numbers makes the image sensor more sensitive to light. Therefore, less light is needed will be needed
to obtain a properly exposed picture.
Next is an example if you are using a Digital Slr in its manual mode. Lets say you are trying to shoot a fast
moving subject. Your camera is set on ISO 100. According to your cameras' exposure meter, in order to obtain a
proper exposure, you must set your aperture to its maximum opening, (lets just use F3,5) and use a shutter
speed of 1/60. However, the shutter speed 1/60 might not be fast enough to "freeze" the action. (moving
subjects might be blurred in an image when you are using slower shutter speeds).
Change your camera setting from ISO 100 to ISO 200. That will decrease the amount of light the camera image
sensor will need for a good exposure. You will then be able to increase your shutter speed from 1/60 to 1/125
to get a properly exposed image. If that shutter speed isn't fast enough, change from ISO 200 to ISO 400. Then
increase the shutter speed to 1/250. (this example assumes the shutter speed of 1/250 was fast enough to
"freeze" the action). You will then have a nicely exposed image without any blur in it.
Lower ISO numbers are better. While it is a great thing to be able to increase your camera's ISO rating in
order to get the shot you want, there is a down side to doing it. The down side is called "digital camera noise".
The higher your ISO setting, the more noise you will see in your picture. Noise is tiny dots or specks in the
image that are generated when the sensor sensitivity is amplified in order to read more light.
Picture #1 taken at IS0 1600 Picture #2 taken at ISO 100
Picture #1 was taken with a setting of ISO 100. Picture #2 was taken with an ISO setting of 1600. You can see
that the picture taken with the ISO setting of 100 is much clearer than the picture with the ISO 1600 setting.
(click either picture to enlarge)
There is always a little noise in a photographic image, but the noise might not be visible unless the image is
greatly enlarged or the ISO setting is set to a pretty high number. Also, digital camera noise will be more visible
in darker areas of the image.
The amount of noise in an image will also vary depending on the image sensor size and make of the camera.
Digital Single Lens Reflex cameras, because of their larger sensor size will exhibit less noise than Digital
Compact cameras at higher ISO settings. In any case, getting the shot with some noise in the picture is better
than no picture at all.
Hopefully, this tutorial has clearly answered the question what is ISO? and how to use it in your digital camera. If
you need more of an explanation of how the camera aperture, camera shutter, and ISO work together to
produce "properly" exposed pictures, check the tutorial, Camera Exposure Basics
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