What Is ISO In DSLR?
ISO is an International Organization for Standardization. It has nothing to do with camera parts. This organization sets the standards for commercial products internationally. Forget to find out any meaning in its full form. Yes! You can relate letter `S` to the Sensitivity which is related to lights for exposing the photos. That’s it!
We need light to see the things around us. Where there is a light, there is a shadow. This is a basic law of nature. We need to expose the photo with balanced light and shadow. The Aperture, Shutter and ISO modes help to achieve this result. These three (Aperture, Shutter, ISO) modes form an exposure triangle. You have to manage them for making good quality photos. All these modes control the light. But there is a difference between all these modes. They do manage the light but in a different way.
Difference Between Aperture, Shutter And ISO:
Aperture: Aperture controls the source of light. (Read here)
Shutter: Shutter is related to the speed of light. (Read here)
ISO: It manages the sensitivity of light.
What does sensitivity mean? There is an electronic sensor in a DSLR camera. This sensor is very sensitive to the light. It works like the human senses. Human eye can sense a light even if the eyelids are closed. If you open your eyelids, the eyes will enhance the power to sense the light. ISO works in the same manner. It goes deeper in the source of light.
Electricity flows in the filament of a bulb. This filament heats up and starts glowing as a bright light. The filament becomes the source of glowing in the light bulb. Sensor can sense the sensitivity around the filament. What If you can increase the sensitivity of the glowing area?. ISO does this job for you.
Imagine, there are 128 candles in the room. Your camera is set to 100 ISO, f/2.8 and 1/60s. If you double the sensitivity of ISO from 100 to 200, you only need 64 candles with same aperture and shutter values. If you increase the ISO from 200 to 400, now you need only 32 candles to capture the same scene. Likewise, With the ISO range of 12800, you need only one candle to get the same results. High ISO number boosts up the power of sensor to sense more light from the same light source. The moment aperture and shutter reach to its limitation, ISO works as a very powerful tool.
In the era of photographic film, there used to be films based on ISO numbers like 25, 50,100, 200 or 400. Sir Henrie-cartier-bresson did photography even on 25 ISO film. Entire world of photographers had emulated his achievements in photography. His work is a real art.
Digital cameras offer much higher range of ISO these days. The lowest ISO range has come down to 64 in Nikon full frame DSLRs. I can imagine that how difficult It had been to make photos with 25 ISO film in the dark without a mounted flash.
Camera manufacturers must have worked very hard to boost the power of ISO. We are very much blessed in this case. I do not use external flash. I am indebted to the camera manufactures for the technology of high ISO range. I shoot my wedding projects with 3000 – 4000 ISO range in the night. I am fearless in playing with ISO. And why not? When the camera manufacturers have put their efforts in bringing up this technology. Photographers can make photos in low light conditions now. That is why, we pay a lot of money to own such cameras. These camera can work better with high ISO range having less noise in post production.
Fear Of High ISO And Noise:
Photographers used to have noise over 400 range of ISO in the photos. That is why, They used to avoid high range of ISO. Cameras also did not have the live view mode. Noise used to be visible only in post production of the images. It can only be managed to a certain level. The whole efforts behind the project used to be ruined. Some photographers used the noise in favor of their work also. But the fear related to noise was transferred from one generation to another. Since then, this fear persists in the photographic world.
Camera manufacturers must have put hard efforts to invent the high ISO technology. They also managed the issue of noise with high ISO range. Today, every camera manufacturer claims to have no noise with high ISO range in an ambient light. If you shoot with high ISO range on RAW format, you will be safe and sound.
We discussed earlier that how slow shutter speed can make the photos blurry (Read here). High ISO range helps me to use fast shutter speed. This is the reason why ISO works as a powerful tool for me. But, I shoot on RAW + JPEG. I would suggest you not to limit yourself. Get out of this fear and play with different ISO range.
Every digital camera has live view mode today. You can always check if there is a noise or not. In such cases, lower the value of ISO and try another shot. There are no thumb rules for best ISO settings. You have to practice it. By doing this, you would also understand the science of light and shadow.
Note: If you want to use the high ISO range, you will have to shoot your project on RAW format. If you shoot in JPEG format with high ISO range, you may have noise.