For the last four lessons, we’ve been dealing with shutter speed and aperture. These two concepts are responsible for keeping exposure in check.
Last time, we particularly dwelled on visualizing the shutter speed at work. The shutter speed manages the amount of light entering your camera by speeding up or slowing down the time your shutter is open.
We mentioned that if you want to shoot faster objects mid-action, you may want to go for a faster shutter speed while a slower shutter speed will be much preferable for long-exposure shots. Note, however, that as you increase your shutter speed, you are decreasing the exposure time of your sensor thus letting in a lesser amount of light.
We completed our discussion on aperture and shutter speed already which brings us in a perfect position to discuss ISO. ISO, together with aperture and shutter speed, forms what is called the exposure triangle - a very critical concept we will discuss in the coming lessons.
Knowing about the ISO is just as important as learning aperture and shutter speed which makes is a necessary knowledge as well when talking about exposure.
How ISO compares
Much like aperture and shutter speed, ISO is a concept that has been in photography since its earliest days. However, among the three, ISO has experienced the biggest change as traditional and film photography transitioned to the digital age.
While both the aperture and your shutter speed can be compared to parts of the eye, the same cannot be said for ISO. Looking for a direct analogy of ISO will take a lengthy biological discussion which defeats the purpose of the analogy itself.
The ISO is the measurement for your camera’s sensitivity to light. In the digital age, the ISO can be easily adjusted the same way you can adjust your aperture and your shutter speed, however, that was not the case before.
In fact, you will learn that back then, ISO was an external feature and photographers had to literally open up their camera in order to change it.
Today, what we will be discussing is how ISO came about and what kind of adjustments should we make in relation to it. We will also define the concept and run through its implications on your style of photography.
The ISO
As promised, we will start by determining the roots of ISO. The ISO has changed through the years and has heavily been affected by the transitioning of film to digital photography.
Back in the day
If you have been reading the previous section of these lessons, during the days of traditional photography, cameras made use of films. ISO was then a measurement of how sensitive the film is to light.
Back then, instead of “ISO,” the term “ASA’ was used since the scale for measurement was developed by the American Standards Association. However, as the International Standards Association adopted the same concept by measuring film sensitivity, the term “ISO” was coined.
If you have seen rolls of films for film cameras, you will notice that it has a number - 100, 200, 400, or 800. Films were made of little crystals and the lower the number on the film, the lower its sensitivity to light was.
As the sensitivity increases, so does the grain thus giving film cameras that textured look.
The Digital Age
As the years passed by and modern technology started penetrating photography, films were replaced by sensors. Although the mechanics are far different, ISO in the digital age and in traditional photography still work on the same principles.
Instead of changing films to change the sensitivity, you can now conveniently set your camera’s ISO to the value you desire to reap its effects. Still, the lower your ISO number is, the less sensitive your sensors will be to light.
The ISO, having experienced a drastic change from film to the sensor technology, still plays a vital role in photography.
Implications of ISO
As mentioned, the ISO affects a lot of things in your image. First and foremost is the amount of light that you will allow to penetrate your sensors.
We discussed that as you increase your ISO number, you are also increasing your sensor’s sensitivity to light. With that said, as your sensors become more sensitive to light, it also allows more light particles to penetrate it thus creating a brighter picture.
If you happen to be in a dark scenario, it may be better to increase your ISO. However, you must also remember that as you increase your ISO, you are also creating more grain in your photo so if you are avoiding that, be sure to find the perfect balance between your ISO, shutter speed, and aperture.
If you choose a high ISO, you will have the freedom of shooting at a faster shutter speed or a smaller aperture. Having your ISO set to 100 or 200 is considered as the standard number where you can get little to no grain at all so be sure to work your way around it.
Conclusion
So that’s it for our lesson on ISO. The ISO is an equally important concept in photography together with aperture and shutter speed. ISO traces its roots from the age of film photography and has gone through a dramatic change due to the emergence of digital photography.
Your ISO measures your camera’s sensitivity to light and you can adjust the ISO to shoot better in bright or dark scenarios. By increasing your ISO you are allowing more light to penetrate your sensors but, at the same time, increasing the grain.
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