lighting in Antelope Canyon

What is the ISO setting

The ISO setting is one of the simplest, yet possibly most important functions of your camera to understand. If you do not understand the ISO setting you may come away from your shoot with either too bright or too dark images.

ISO stands for International Organization of Standardization.  The International Organization of Standardization is a governing body responsible for standardizing sensitivity ratings for camera sensors. In the days of film cameras, the ISO body would rate film’s sensitivity to light, giving it a speed and ASA rating.

When digital cameras became the new norm in photography, the cameras still used the ISO standard to describe a digital sensor’s light sensitivity.  Basically speaking, the lower the number of ISO you have set on your camera means it’s less sensitive to light, while the higher the number the more sensitive to light it will be.

Viewing this lesson in Virtual Reality

As part of my ‘Basics of Using a Camera‘ workshop, I have filmed this lesson to answer the question of ‘what is the f-stop?’ in a virtual reality 360 degree format which is best viewed using a virtual reality headset like the Oculus Quest. However you may also use a cheaper headset like a google cardboard with a smartphone mounted inside, or failing that you can also simply use a smart phone, or your mouse to click and drag through the video on a screen.

For best viewing make sure you select the highest quality of stream.

Click the play symbol to start

Using the ISO Setting

It’s importnant to remember that ISO is one of the three components of exposure in photography.  It affects how bright your image comes out. The ISO also infuences as well as the amount of digital noise, or grain, your image will have. This is more due to the sensor’s quality more than anything but it does cause the effect.  Understanding when and how to raise and lower your ISO will help you achieve the look you want.

Remember ISO value and exposure value are not the same thing. While the ISO setting controls the light sensitivity of your sensor, it doesn’t determine how much light is captured by the camera. That is the task of the other two settings you have control over being the combined settings of your camera’s shutter speed and aperture, or f-stop.

With all other settings being the same if you were to take a phoot of the same scene, and only changing the ISO setting in between shots you will get the same effect as demonstrated below.

Why change the ISO?

Digital cameras are super convenient in being able to change the ISO settings on the fly. Film cemeras never had that ability due to the fact that the ISO rating of the physical film is what you had to work with until you were able to change rolls. Changing the ISO setting makes it easy for a photographer to adapt to different situations and create a well exposed image much easier when simply exposing using the aperture and shutter speed settings.

Think about these following situations

  • You may find yourself stuck with a slow lens with a high minimum f-stop rating, in order to brighten the image instead of lowering the aperture rating, you’re able to raise the ISO setting to brighten your image.
  • Holding a camera by hand means you’re unable to lower your shutter speed beyond a certain point and still retain a sharp image, there fore you may wish to raise the ISO sensitivity to brighten the imaghe instead of slowing the shutter speed.
  • Taking photos in dark situations means that sometimes simply lowering the aperture rating and shutter speed would not be enough. Perhaps in a dark room, or taking photos of stars.

Auto ISO

Modern digital cameras have a nifty ability to set ISO to auto, meaning the camera will take the settings set with the shutter speed and aperture and calculate the needed sensor sensitivity to create a pleasing exposure. This is useful as you may wish to force a short depth of field with a lower f-stop setting, and you may also want a very fast shutter speed to freeze motion, so setting the ISO to auto means you can set those options and have the camera automatically set the correct ISO setting.