I know you have purchased a new camera and are ready to go outside and hit that shutter. But before that, it is important to understand the three pillars of photography.
In our previous article on Aperture, we learnt about how we can manipulate the light that enters the camera and also how to get the details from our subject. Like Aperture, even ISO and shutter speed are factors that govern the brightness that your final image carries. A combinational use of these three should be clear before that shutter bug takes on the streets.
Why such a weird name?
Many of you must have confused the term ISO in photography with the International Organization of Standards and surprisingly, even in photography ISO stands for the same. Earlier, during that old ‘film rolls’ era, the films were given a specific ISO rating such as ISO 100, ISO 400 , ISO 800 etc. This way, it became a new term for photographers in the world of cameras.
What is ISO?
Now that we know where this term comes from, let us understand its in and out. ISO is the level of sensitivity of your camera sensor to the exposed light.
Let me put it in a simple way. What happens when you are watching a movie in a theater and after 2 hours or so, you come out of that door and suddenly the bright sunlight hits your eyes? You are unable to see clearly for few seconds, right? Everything will seem so bright. This is because our eyes are very sensitive to light.
You can relate the same phenomenon to the camera sensor. ISO is the numerical representation of the sensitivity level of the sensor to the exposed light.
How does the ISO work?
Every camera has an ISO range that stretches from its minimum value to the maximum value. The minimum value is often referred to as the Base ISO. Usually the base ISO is around 100.
Depending on the light conditions you are shooting in, the ISO should be selected carefully. While shooting indoors, for the mid-range cameras, you should keep the ISO around 400 and should keep a slow shutter speed so as to let the light enter the camera for a longer time. If you increase the ISO to around 1600, the image will come out to be grainy or noisy as you are forcing the sensor to capture the subject in a very low light at such a high ISO.
When and how to choose the ISO ?
When the digital cameras were launched, people used to figure out the correct ISO setting by trial and error method. Now we have a specific range of ISO values for different light conditions.
While shooting outdoors, in bright sunlight, always keep the ISO between 200 to 400. If you increase it, you will lose the details of the subject and everything will be bright and overexposed.
When you are shooting in a low light (like when the sun is about to set) and you need to click some moving objects, you have to bump the ISO to around 800. Increasing it more than this will get grains or noise in the image (3rd image).
Provided your aperture is kept constant:
- Low light and stationary subject : use low ISO and slow shutter speed.
- Low light and moving object : use high ISO and a bit fast shutter speed.
- Bright light : use low ISO and you may choose a suitable shutter speed.