What is ISO in digital photography?

In traditional photography - film cameras, ISO or ASA is a parameter that indicates how sensitive the film is to light. ISO in digital cameras is similar, it is one of the three important parameters to help you take well-exposed photos. The other two important parameters are Aperture and Shutter Speed

What is ISO in digital photography? Picture 1 ISO in digital photography

ISO in digital photography

In digital photography, ISO is the sensitivity of the image sensor - Censor. They are expressed with the values ​​100, 200, 400, 800, 1600,. and the same principles apply as in film cameras, the smaller the number, the less sensitive the image to light and images. The image will be less grainy.

What is ISO in digital photography? Picture 2 Compare photos taken with different ISO parameters

Setting the ISO to a higher value is often used when shooting in darker situations while still shooting at a high speed.

ISO 100 is often the default choice for sharp, low-noise images.

Most people tend to leave their digital cameras in Auto Mode, then the camera will choose the appropriate ISO depending on the conditions of the shooting environment, however the camera will try to keep the ISO the lower the better.

Nowadays, most cameras allow you to choose your own ISO. As you change the ISO, you'll notice it affects the aperture - Aperture and speed - Shutter Speed ​​is needed to get a well-exposed photo. For example, when you change the ISO setting from 100 to 400, you will find that you can take pictures at a higher speed and/or a smaller aperture.

How to set the ISO of a digital camera

Digital cameras do not always allow you to change the ISO setting, especially when shooting with automatic modes - Auto Mode or preset - Scene Mode. 

When you want to set the ISO, switch to the mode that allows you to choose the ISO yourself by exiting the auto mode - Auto and switching to one of the manual shooting modes - Manual, speed priority - Shutter Priority, Aperture Priority - Aperture Priority or Program - Program.

Aperture-priority or manual shooting modes are often used when you want to change the ISO.

For regular cameras, you probably need to go to the settings menu - Menu and find the setting for ISO. Then select the ISO value you want or choose automatic.

For higher-end cameras, there will probably be a dedicated ISO button on the camera. Simply press it and rotate one of the dials to change the camera's ISO setting.

Some other cameras may have a dedicated dial dedicated to setting ISO with different values, you just need to rotate the dial to select.

What is ISO in digital photography? Picture 3 Dedicated dial dedicated to setting ISO with different values

If you don't see a button labeled ISO, it's still possible that your camera will allow you to program it to turn a multifunction button into an ISO button. See the manual that came with your digital camera for how to use it. 

Issues to pay attention to when choosing ISO

1. Lighting - Is the subject well lit?
2. Noise - Do you want a photo with more or less noise?
3. Tripod - Do you use a tripod - Tripod?
4. Motion - Is the subject moving or stationary?

If you're shooting in a well-lit area or want your photos to be less grainy, or you're using a tripod and the subject you want to shoot is still, it's generally best to use a low ISO setting.

However, if you are shooting at night or you do not care about the image will be grainy or the subject you want to capture is moving, you need to consider increasing the ISO as it will allow you to shoot at a higher speed without delay. still get a well-exposed photo.

Always remember that the higher the ISO, the more grainy the image will be.

What is ISO in digital photography? Picture 4 The image on the left was taken at ISO 100 and the image on the right is grainy when taken at ISO 3200

Situations where you might need to raise your ISO

1. When shooting indoor sporting events, where the subject is always moving fast and the light is very limited. Increasing the ISO will help you capture this scene at high speed.
2. When shooting in concerts, also in low light and do not use flash. Increasing the ISO will make your photos brighter.
3. When shooting in art galleries, pictures, . are places where there is often insufficient light and the use of Flash is not allowed. Increasing the ISO will make your photos brighter.
4. When shooting at a party, birthday, . blowing out candles in a dark room will give a good photo but it will be ruined if you use the flash. Increasing the ISO will help you capture this scene without Flash.

ISO is a very important factor to understand in digital photography if you want to gain control of your digital camera. Try with different ISO settings to get the photos you want

David Pac

Update 08 May 2023