The International’s Organization of Standardization, more commonly known as ISO is the numeric value system used for identifying brightness. Though it originates from film cameras the values have been continued in use with digital cameras, a welcome continuity.
ISO At A Glance
A quick explanation for the use of this setting on digital cameras is that ISO values determine the brightness of the photograph captured. Low ISO (ISO 100) allows very little brightness in the photo while high ISO (ISO 6400) allows a huge amount of brightness. Unfortunately ISO is limited in it’s abilities to brighten an image with good clarity and sharpness without noise, so to fully capture the full spectrum of your cameras abilities one must use aperture, shutter speed and ISO simultaneously. Some would argue that in the age of digital cameras that ISO should be the last of the three to be considered and adjusted and I tend to agree with that line of thought. Aperture and shutter speed directly influence the amount of light in the shot, whereas ISO brightens the image. Ideally shots are taken with the lowest viable ISO. Below is a series of images shot with a 1/25 shutter speed and F10.
Keeping ISO Low
In order to keep ISO low while maintaining viable brightness for an image one would use a longer shutter speed. This comes with draw backs, as maintaining the camera steadily can be rather difficult in a lot of scenarios, but equipment such as monopods and tripods make this considerably easier. The other issue that comes with long shutter speeds is motion blur. This ruins the sharpness of the image and often renders it unusable. Using higher ISO with lower shutter speed is a better combination for capturing movement. Below is side by side comparison of a bottle taken with different shutter speeds with ISO 100 and F10. While the practicality of incredibly long shutter speeds is limited, this acts as a visual aid to the concept.
The third control used is aperture. Its values are shown in a F# format, aperture plays a large role in brightness as well as focus in the image but we will only be covering the brightness at the moment. Beginners often ignore their aperture settings in favour for ISO control, but ultimately it is a very important setting that should be closely controlled to ensure subjects are well captured. Below is a series of images that show aperture settings with 1/10 shutter speed and ISO 100.