Photo Clinic Vol 9 2010

The Importance of ISO


One of the best innovations to come out of the digital age is the ability to change ISO settings AT ANY TIME, with the flick of a button and dial. Long gone are the film days when you were stuck with the ISO settings of the film for the duration of that particular roll. For example, if the roll of film was rated at ISO 100 and you needed to up that value to say ISO 800 or 1600 to cover a scene unfolding before you in a low light situation, the only thing you could do was to wind off that roll and put in a new one (if you had a suitable one), with a higher ISO speed rating. (Sometimes we could ask that the film lab push processes the film by one or two ISO stops but then we would blow whatever we had recorded on the film prior to this, and we could never achieve a three or four time increase in the ISO value). Changing film rolls to cover the dynamics of a lighting scene ended up being a costly exercise and given the time involved to complete the task, the subject matter may have gone or the opportunity lost.

What is ISO? Technically it stands for International Standards Organisation and refers to the measure of light sensitivity of the digital sensor. In most digital cameras the native speed of the sensor is set to ISO 100. The ISO value can be increased by electronically amplifying the signal to the sensor. The downside is a reduction in image quality due to digital noise (spotty flecks of colour more noticeable in the darker areas of an image), or what was known as grain in film parlance.

With some of the latest generation of Canon and Nikon cameras, ISO ratings now can extend up to an incredible 102,400, an unbelievable notion only a few years back. Sure, the images are going to be noisy and hardly of magazine quality, but it effectively means that you can shoot in dark situations without flash. This will be especially useful in indoor concerts or sporting venues where flash may be banned or when shooting wildlife where flash may startle the subject. These images can be enhanced with in-camera noise reduction settings or noise suppression software in post production. Given its present limitations you are hardly going to want to set the ISO values to such a high setting, but it could mean the difference between getting a shot or not at all, and it won’t be long before technology reaches the stage that ISO 102,400 will be highly useable.

Read the rest in the latest Fishing Wild magazine.