ISO Speed is one of the three elements of camera exposure (photography triangle). In which, each novice photographer should learn camera ISO speed thoroughly (and also the other two elements of exposure; Aperture and Shutter Speed) to master how to use a professional camera. This post will try to explain camera ISO speed as simple as possible.
The Definition of ISO
By definition, ISO is the level of the camera sensor sensitivity towards the light. The higher you set the ISO setting, the more sensitive the camera sensor towards the light.
To get a clear understanding about Camera ISO setting (or ASA in the case of film photographic), a bee community may be the most precise to illustrate how a camera ISO works. Take a read at the illustrations below.
- An ISO is a worker bee. If you set the camera ISO speed at 100, it means you have 100 worker bees.
- If you set the camera ISO speed at 200, it means you have 200 worker bees.
The task of each worker bee is picking up the light that enters through the camera lens and then makes an image. If you set an identical lens and the aperture equally at f/3.5, and you set the ISO at 200 while I only set the ISO at 100 (think again about the illustration above), who’s image will be finished earlier?
Camera ISO Speed
To understand more about camera ISO speed, below are the details of the answer with a broader point of view about ISO Speed.
- When you add the ISO setting from 100 to 200 (the aperture is always constant – you lock the aperture at f/3.5 or via the Aperture Priority mode – A or Av), then you shorten the time that is required in making a photograph in the camera sensor until a half of (two times faster) the shutter speed at 1/125 sec to 1/250 sec.
- When you add more ISO at 400, it means you cut back to half again in making pictures, which is at 1/500 sec.
- Each time you shorten the exposure time as much as a half, it means you raise the exposure by 1 stop.
Here’s the set of examples of Camera ISO Speed measurement:
- ISO 100 – 1 second
- ISO 200 – 0.5 of a second (500 milliseconds)
- ISO 400 – 0.25 of a second (250 milliseconds)
- ISO 800 – 0.125 of a second (125 milliseconds)
- ISO 1600 – 0.0625 of a second (62.5 milliseconds)
- ISO 3200 – 0.03125 of a second (32.25 milliseconds)
You can also try this understanding to the case of the Aperture. In which, try to set the camera shutter speed remains constant at 1/125 (or through Shutter Priority mode – S or Tv), and then changing the camera ISO setting in multiples of two. For example, you can change it from 100 to 200, then to 400, etc. Then, take a look at the changes at the magnitude of your camera aperture.
The Right Time to Use Low ISO Speed
Each time you are taking a snapshot, try to always stick to the lowest ISO. The best ISO speed is specifically ISO 200 or 100 if it’s possible. The best condition to the lowest ISO is when there is ample of light around the object. If you set your camera ISO speed to the lowest could withstand the object detail and quality when it comes to converting to photo. However, there are some conditions where you might want to set low ISO in faint light environments. For example, you mount your camera on a tripod to maintain the camera position doesn’t shake when taking a picture, in which your camera need more time to capture the moving scene of an object. So, you can use low ISO either in a dim or bright environment, but it depends on the type of photo you need.
The Right Time to Increase ISO Speed
When you need to take a snapshot in a low light environment, it’s the right time to increase your ISO camera setting. Increasing the camera ISO speed, the camera can quickly capture an image. It is good for you to capture an image indoor without using a flash. So, the photo result would be without blur. Meanwhile, increasing the camera ISO speed is good when you will do ultra-fast snapshots, such as real bird picture. But, make sure that if there is noise in the photo is not a matter for you. In other words, customize it to your photo taking needs.
Nowadays, there are many new DSLR cameras with “Auto ISO” feature. The Auto ISO feature is good in dim environments. The advantage of Auto ISO is a photographer can set the highest ISO to a particular number. Then, the ISO will be increasing depend on the volume of light in an environment.